diff --git a/browser/base/content/test/chrome/test_aboutCrashed.xhtml b/browser/base/content/test/chrome/test_aboutCrashed.xhtml
index df48694e38aa..8bad1ac80d91 100644
--- a/browser/base/content/test/chrome/test_aboutCrashed.xhtml
+++ b/browser/base/content/test/chrome/test_aboutCrashed.xhtml
@@ -57,7 +57,7 @@
       frame1.docShell.chromeEventHandler.removeAttribute("crashedPageTitle");
 
       SimpleTest.is(frame1.contentDocument.documentURI,
-                    "about:tabcrashed?e=tabcrashed&u=http%3A//www.example.com/1&c=UTF-8&d=pageTitle",
+                    "about:tabcrashed?e=tabcrashed&u=http%3A//www.example.com/1&c=UTF-8&f=regular&d=pageTitle",
                     "Correct about:tabcrashed displayed for page with title.");
 
       errorPageReady = waitForErrorPage(frame2);
@@ -66,7 +66,7 @@
       await errorPageReady;
 
       SimpleTest.is(frame2.contentDocument.documentURI,
-                    "about:tabcrashed?e=tabcrashed&u=http%3A//www.example.com/2&c=UTF-8&d=%20",
+                    "about:tabcrashed?e=tabcrashed&u=http%3A//www.example.com/2&c=UTF-8&f=regular&d=%20",
                     "Correct about:tabcrashed displayed for page with no title.");
 
       SimpleTest.finish();
diff --git a/browser/base/content/test/chrome/test_aboutRestartRequired.xhtml b/browser/base/content/test/chrome/test_aboutRestartRequired.xhtml
index 4b8293e45001..17cd84bd73ac 100644
--- a/browser/base/content/test/chrome/test_aboutRestartRequired.xhtml
+++ b/browser/base/content/test/chrome/test_aboutRestartRequired.xhtml
@@ -55,7 +55,7 @@
       frame1.docShell.chromeEventHandler.removeAttribute("crashedPageTitle");
 
       SimpleTest.is(frame1.contentDocument.documentURI,
-                    "about:restartrequired?e=restartrequired&u=http%3A//www.example.com/1&c=UTF-8&d=%20",
+                    "about:restartrequired?e=restartrequired&u=http%3A//www.example.com/1&c=UTF-8&f=regular&d=%20",
                     "Correct about:restartrequired displayed for page with title.");
 
       errorPageReady = waitForErrorPage(frame2);
@@ -64,7 +64,7 @@
       await errorPageReady;
 
       SimpleTest.is(frame2.contentDocument.documentURI,
-                    "about:restartrequired?e=restartrequired&u=http%3A//www.example.com/2&c=UTF-8&d=%20",
+                    "about:restartrequired?e=restartrequired&u=http%3A//www.example.com/2&c=UTF-8&f=regular&d=%20",
                     "Correct about:restartrequired displayed for page with no title.");
 
       SimpleTest.finish();
diff --git a/browser/components/contextualidentity/test/browser/browser_broadcastchannel.js b/browser/components/contextualidentity/test/browser/browser_broadcastchannel.js
index 4bce3fbc7f96..e4c4fae7f653 100644
--- a/browser/components/contextualidentity/test/browser/browser_broadcastchannel.js
+++ b/browser/components/contextualidentity/test/browser/browser_broadcastchannel.js
@@ -18,6 +18,48 @@ async function openTabInUserContext(uri, userContextId) {
   return { tab, browser };
 }
 
+// Opens `uri' in a new <iframe mozbrowser> with the provided userContextId.
+// Returns the newly opened browser.
+async function addBrowserFrameInUserContext(uri, userContextId) {
+  // Create a browser frame with the user context and uri
+  const browser = document.createElementNS(
+    "http://www.w3.org/1999/xhtml",
+    "iframe"
+  );
+  browser.setAttribute("remote", "true");
+  browser.setAttribute("usercontextid", userContextId);
+  browser.setAttribute("mozbrowser", "true");
+  // `noisolation = true` means `OA.mInIsolatedMozBrowser = false` which matches
+  // the default for a XUL browser. It is indepedent from user contexts.
+  browser.setAttribute("noisolation", "true");
+  browser.setAttribute("src", uri);
+  gBrowser.tabpanels.appendChild(browser);
+
+  // Create a XUL browser-like API expected by test helpers
+  Object.defineProperty(browser, "messageManager", {
+    get() {
+      return browser.frameLoader.messageManager;
+    },
+    configurable: true,
+    enumerable: true,
+  });
+
+  await browserFrameLoaded(browser);
+
+  return { browser };
+}
+
+function browserFrameLoaded(browser) {
+  let event = "BrowserTestUtils:ContentEvent:load";
+  return BrowserTestUtils.waitForEvent(browser, event);
+}
+
+function removeBrowserFrame({ browser }) {
+  browser.remove();
+  // Clean up Browser API parent-side data
+  delete window._browserElementParents;
+}
+
 async function runTestForReceiver(receiver) {
   let channelName = "contextualidentity-broadcastchannel";
 
@@ -81,3 +123,13 @@ add_task(async function test() {
   await runTestForReceiver(receiver);
   gBrowser.removeTab(receiver.tab);
 });
+
+add_task(async function test() {
+  info("Checking broadcast channel with <iframe mozbrowser> receiver");
+  await SpecialPowers.pushPrefEnv({
+    set: [["dom.mozBrowserFramesEnabled", true]],
+  });
+  let receiver = await addBrowserFrameInUserContext(URI, 2);
+  await runTestForReceiver(receiver);
+  removeBrowserFrame(receiver);
+});
diff --git a/docshell/base/nsDocShell.cpp b/docshell/base/nsDocShell.cpp
index 3d6b5a11de0b..767985c0cf45 100644
--- a/docshell/base/nsDocShell.cpp
+++ b/docshell/base/nsDocShell.cpp
@@ -354,6 +354,7 @@ nsDocShell::nsDocShell(BrowsingContext* aBrowsingContext,
       mLoadType(0),
       mDefaultLoadFlags(nsIRequest::LOAD_NORMAL),
       mFailedLoadType(0),
+      mFrameType(FRAME_TYPE_REGULAR),
       mDisplayMode(nsIDocShell::DISPLAY_MODE_BROWSER),
       mJSRunToCompletionDepth(0),
       mTouchEventsOverride(nsIDocShell::TOUCHEVENTS_OVERRIDE_NONE),
@@ -1841,6 +1842,21 @@ nsDocShell::GetFullscreenAllowed(bool* aFullscreenAllowed) {
   return parent->GetFullscreenAllowed(aFullscreenAllowed);
 }
 
+NS_IMETHODIMP
+nsDocShell::SetFullscreenAllowed(bool aFullscreenAllowed) {
+  if (!nsIDocShell::GetIsMozBrowser()) {
+    // Only allow setting of fullscreenAllowed on content/process boundaries.
+    // At non-boundaries the fullscreenAllowed attribute is calculated based on
+    // whether all enclosing frames have the "mozFullscreenAllowed" attribute
+    // set to "true". fullscreenAllowed is set at the process boundaries to
+    // propagate the value of the parent's "mozFullscreenAllowed" attribute
+    // across process boundaries.
+    return NS_ERROR_UNEXPECTED;
+  }
+  mFullscreenAllowed = (aFullscreenAllowed ? PARENT_ALLOWS : PARENT_PROHIBITS);
+  return NS_OK;
+}
+
 hal::ScreenOrientation nsDocShell::OrientationLock() {
   return mOrientationLock;
 }
@@ -2622,8 +2638,21 @@ void nsDocShell::MaybeClearStorageAccessFlag() {
 
 NS_IMETHODIMP
 nsDocShell::GetInProcessSameTypeParent(nsIDocShellTreeItem** aParent) {
-  if (BrowsingContext* parentBC = mBrowsingContext->GetParent()) {
-    *aParent = do_AddRef(parentBC->GetDocShell()).take();
+  NS_ENSURE_ARG_POINTER(aParent);
+  *aParent = nullptr;
+
+  if (nsIDocShell::GetIsMozBrowser()) {
+    return NS_OK;
+  }
+
+  nsCOMPtr<nsIDocShellTreeItem> parent =
+      do_QueryInterface(GetAsSupports(mParent));
+  if (!parent) {
+    return NS_OK;
+  }
+
+  if (parent->ItemType() == mItemType) {
+    parent.swap(*aParent);
   }
   return NS_OK;
 }
@@ -3867,6 +3896,10 @@ nsresult nsDocShell::LoadErrorPage(nsIURI* aURI, const char16_t* aURL,
   }
   errorPageUrl.AppendLiteral("&c=UTF-8");
 
+  nsAutoCString frameType(FrameTypeToString(mFrameType));
+  errorPageUrl.AppendLiteral("&f=");
+  errorPageUrl.AppendASCII(frameType.get());
+
   nsCOMPtr<nsICaptivePortalService> cps = do_GetService(NS_CAPTIVEPORTAL_CID);
   int32_t cpsState;
   if (cps && NS_SUCCEEDED(cps->GetState(&cpsState)) &&
@@ -4698,7 +4731,9 @@ nsDocShell::SetIsActive(bool aIsActive) {
       continue;
     }
 
-    docshell->SetIsActive(aIsActive);
+    if (!docshell->GetIsMozBrowser()) {
+      docshell->SetIsActive(aIsActive);
+    }
   }
 
   // Restart or stop meta refresh timers if necessary
@@ -8987,7 +9022,8 @@ nsresult nsDocShell::InternalLoad(nsDocShellLoadState* aLoadState,
     }
   }
 
-  bool isTopLevelDoc = mBrowsingContext->IsTopContent();
+  bool isTopLevelDoc =
+      mItemType == typeContent && (!IsFrame() || GetIsMozBrowser());
 
   OriginAttributes attrs = GetOriginAttributes();
   attrs.SetFirstPartyDomain(isTopLevelDoc, aLoadState->URI());
@@ -12367,6 +12403,46 @@ nsDocShell::GetCanExecuteScripts(bool* aResult) {
   return NS_OK;
 }
 
+/* [infallible] */
+NS_IMETHODIMP nsDocShell::SetFrameType(FrameType aFrameType) {
+  mFrameType = aFrameType;
+  return NS_OK;
+}
+
+/* [infallible] */
+NS_IMETHODIMP nsDocShell::GetFrameType(FrameType* aFrameType) {
+  *aFrameType = mFrameType;
+  return NS_OK;
+}
+
+/* [infallible] */
+NS_IMETHODIMP nsDocShell::GetIsMozBrowser(bool* aIsMozBrowser) {
+  *aIsMozBrowser = (mFrameType == FRAME_TYPE_BROWSER);
+  return NS_OK;
+}
+
+uint32_t nsDocShell::GetInheritedFrameType() {
+  if (mFrameType != FRAME_TYPE_REGULAR) {
+    return mFrameType;
+  }
+
+  nsCOMPtr<nsIDocShellTreeItem> parentAsItem;
+  GetInProcessSameTypeParent(getter_AddRefs(parentAsItem));
+
+  nsCOMPtr<nsIDocShell> parent = do_QueryInterface(parentAsItem);
+  if (!parent) {
+    return FRAME_TYPE_REGULAR;
+  }
+
+  return static_cast<nsDocShell*>(parent.get())->GetInheritedFrameType();
+}
+
+/* [infallible] */
+NS_IMETHODIMP nsDocShell::GetIsInMozBrowser(bool* aIsInMozBrowser) {
+  *aIsInMozBrowser = (GetInheritedFrameType() == FRAME_TYPE_BROWSER);
+  return NS_OK;
+}
+
 /* [infallible] */
 NS_IMETHODIMP nsDocShell::GetIsTopLevelContentDocShell(
     bool* aIsTopLevelContentDocShell) {
diff --git a/docshell/base/nsDocShell.h b/docshell/base/nsDocShell.h
index 42b0ceabb609..47ea79484519 100644
--- a/docshell/base/nsDocShell.h
+++ b/docshell/base/nsDocShell.h
@@ -569,6 +569,18 @@ class nsDocShell final : public nsDocLoader,
     return uint32_t(aTimeUsec / PR_USEC_PER_SEC);
   }
 
+  static const nsCString FrameTypeToString(uint32_t aFrameType) {
+    switch (aFrameType) {
+      case FRAME_TYPE_BROWSER:
+        return NS_LITERAL_CSTRING("browser");
+      case FRAME_TYPE_REGULAR:
+        return NS_LITERAL_CSTRING("regular");
+      default:
+        NS_ERROR("Unknown frame type");
+        return EmptyCString();
+    }
+  }
+
   virtual ~nsDocShell();
 
   //
@@ -997,6 +1009,7 @@ class nsDocShell final : public nsDocLoader,
   bool IsPrintingOrPP(bool aDisplayErrorDialog = true);
   bool IsNavigationAllowed(bool aDisplayPrintErrorDialog = true,
                            bool aCheckIfUnloadFired = true);
+  uint32_t GetInheritedFrameType();
   nsIScrollableFrame* GetRootScrollFrame();
   nsIChannel* GetCurrentDocChannel();
   nsresult EnsureScriptEnvironment();
@@ -1216,6 +1229,9 @@ class nsDocShell final : public nsDocLoader,
   uint32_t mDefaultLoadFlags;
   uint32_t mFailedLoadType;
 
+  // Are we a regular frame, a browser frame, or an app frame?
+  FrameType mFrameType;
+
   // This represents the CSS display-mode we are currently using. This is mostly
   // used for media queries.
   DisplayMode mDisplayMode;
diff --git a/docshell/base/nsIDocShell.idl b/docshell/base/nsIDocShell.idl
index 700845dbd143..f730653b9614 100644
--- a/docshell/base/nsIDocShell.idl
+++ b/docshell/base/nsIDocShell.idl
@@ -684,6 +684,32 @@ interface nsIDocShell : nsIDocShellTreeItem
    */
   [noscript] void notifyScrollObservers();
 
+  /**
+   * The type of iframe that this docshell lives.
+   */
+  cenum FrameType : 8 {
+    FRAME_TYPE_REGULAR = 0,
+    FRAME_TYPE_BROWSER = 1,
+  };
+  [infallible] attribute nsIDocShell_FrameType frameType;
+
+  /**
+   * Returns true if this docshell corresponds to an <iframe mozbrowser>.
+   * <xul:browser> returns false here.
+   */
+  [infallible] readonly attribute boolean isMozBrowser;
+
+  /**
+   * Returns true if this docshell corresponds to an <iframe mozbrowser>, or
+   * if this docshell is contained in an <iframe mozbrowser>. <xul:browser>
+   * returns false here.
+   *
+   * To compute this value, we walk up the docshell hierarchy.  If we encounter
+   * a docshell with isMozBrowser before we hit the end of the hierarchy,
+   * we return true.  Otherwise, we return false.
+   */
+  [infallible] readonly attribute boolean isInMozBrowser;
+
   /**
    * Returns true if this docshell is the top level content docshell.
    */
@@ -691,7 +717,7 @@ interface nsIDocShell : nsIDocShellTreeItem
 
   /**
    * Like nsIDocShellTreeItem::GetSameTypeParent, except this ignores <iframe
-   * mozbrowser> boundaries. Which no longer exist.
+   * mozbrowser> boundaries.
    *
    * @deprecated: Use `BrowsingContext::GetParent()` in the future.
    */
@@ -753,6 +779,8 @@ interface nsIDocShell : nsIDocShellTreeItem
    */
   [infallible] readonly attribute boolean fullscreenAllowed;
 
+  void setFullscreenAllowed(in boolean allowed);
+
   [notxpcom] uint32_t orientationLock();
   [notxpcom] void setOrientationLock(in uint32_t orientationLock);
 
diff --git a/dom/base/InProcessBrowserChildMessageManager.cpp b/dom/base/InProcessBrowserChildMessageManager.cpp
index ccb88fa82627..c827efcc623f 100644
--- a/dom/base/InProcessBrowserChildMessageManager.cpp
+++ b/dom/base/InProcessBrowserChildMessageManager.cpp
@@ -46,8 +46,8 @@ InProcessBrowserChildMessageManager::Create(nsDocShell* aShell,
 
 bool InProcessBrowserChildMessageManager::DoSendBlockingMessage(
     JSContext* aCx, const nsAString& aMessage, StructuredCloneData& aData,
-    JS::Handle<JSObject*> aCpows, nsTArray<StructuredCloneData>* aRetVal,
-    bool aIsSync) {
+    JS::Handle<JSObject*> aCpows, nsIPrincipal* aPrincipal,
+    nsTArray<StructuredCloneData>* aRetVal, bool aIsSync) {
   SameProcessMessageQueue* queue = SameProcessMessageQueue::Get();
   queue->Flush();
 
@@ -55,8 +55,8 @@ bool InProcessBrowserChildMessageManager::DoSendBlockingMessage(
     SameProcessCpowHolder cpows(JS::RootingContext::get(aCx), aCpows);
     RefPtr<nsFrameMessageManager> mm = mChromeMessageManager;
     RefPtr<nsFrameLoader> fl = GetFrameLoader();
-    mm->ReceiveMessage(mOwner, fl, aMessage, true, &aData, &cpows, aRetVal,
-                       IgnoreErrors());
+    mm->ReceiveMessage(mOwner, fl, aMessage, true, &aData, &cpows, aPrincipal,
+                       aRetVal, IgnoreErrors());
   }
   return true;
 }
@@ -81,13 +81,13 @@ class nsAsyncMessageToParent : public nsSameProcessAsyncMessageBase,
 
 nsresult InProcessBrowserChildMessageManager::DoSendAsyncMessage(
     JSContext* aCx, const nsAString& aMessage, StructuredCloneData& aData,
-    JS::Handle<JSObject*> aCpows) {
+    JS::Handle<JSObject*> aCpows, nsIPrincipal* aPrincipal) {
   SameProcessMessageQueue* queue = SameProcessMessageQueue::Get();
   JS::RootingContext* rcx = JS::RootingContext::get(aCx);
   RefPtr<nsAsyncMessageToParent> ev =
       new nsAsyncMessageToParent(rcx, aCpows, this);
 
-  nsresult rv = ev->Init(aMessage, aData);
+  nsresult rv = ev->Init(aMessage, aData, aPrincipal);
   if (NS_FAILED(rv)) {
     return rv;
   }
diff --git a/dom/base/InProcessBrowserChildMessageManager.h b/dom/base/InProcessBrowserChildMessageManager.h
index b601aa030778..1a3dc22c9b24 100644
--- a/dom/base/InProcessBrowserChildMessageManager.h
+++ b/dom/base/InProcessBrowserChildMessageManager.h
@@ -76,11 +76,13 @@ class InProcessBrowserChildMessageManager final
   virtual bool DoSendBlockingMessage(JSContext* aCx, const nsAString& aMessage,
                                      StructuredCloneData& aData,
                                      JS::Handle<JSObject*> aCpows,
+                                     nsIPrincipal* aPrincipal,
                                      nsTArray<StructuredCloneData>* aRetVal,
                                      bool aIsSync) override;
   virtual nsresult DoSendAsyncMessage(JSContext* aCx, const nsAString& aMessage,
                                       StructuredCloneData& aData,
-                                      JS::Handle<JSObject*> aCpows) override;
+                                      JS::Handle<JSObject*> aCpows,
+                                      nsIPrincipal* aPrincipal) override;
 
   void GetEventTargetParent(EventChainPreVisitor& aVisitor) override;
 
diff --git a/dom/base/MessageBroadcaster.h b/dom/base/MessageBroadcaster.h
index e123bb129f29..62d93bd36c71 100644
--- a/dom/base/MessageBroadcaster.h
+++ b/dom/base/MessageBroadcaster.h
@@ -30,7 +30,7 @@ class MessageBroadcaster : public MessageListenerManager {
                              JS::Handle<JS::Value> aObj,
                              JS::Handle<JSObject*> aObjects,
                              mozilla::ErrorResult& aError) {
-    DispatchAsyncMessage(aCx, aMessageName, aObj, aObjects,
+    DispatchAsyncMessage(aCx, aMessageName, aObj, aObjects, nullptr,
                          JS::UndefinedHandleValue, aError);
   }
   uint32_t ChildCount() { return mChildManagers.Length(); }
diff --git a/dom/base/MessageManagerGlobal.cpp b/dom/base/MessageManagerGlobal.cpp
index f8bd98629912..a29d51641657 100644
--- a/dom/base/MessageManagerGlobal.cpp
+++ b/dom/base/MessageManagerGlobal.cpp
@@ -37,6 +37,14 @@ void MessageManagerGlobal::Dump(const nsAString& aStr) {
   fflush(stdout);
 }
 
+void MessageManagerGlobal::PrivateNoteIntentionalCrash(ErrorResult& aError) {
+  if (XRE_IsContentProcess()) {
+    NoteIntentionalCrash("tab");
+    return;
+  }
+  aError.Throw(NS_ERROR_NOT_IMPLEMENTED);
+}
+
 void MessageManagerGlobal::Atob(const nsAString& aAsciiString,
                                 nsAString& aBase64Data, ErrorResult& aError) {
   aError = nsContentUtils::Atob(aAsciiString, aBase64Data);
diff --git a/dom/base/MessageManagerGlobal.h b/dom/base/MessageManagerGlobal.h
index 44b77737e5ca..4e8b4a51a24e 100644
--- a/dom/base/MessageManagerGlobal.h
+++ b/dom/base/MessageManagerGlobal.h
@@ -59,13 +59,14 @@ class MessageManagerGlobal {
   void SendAsyncMessage(JSContext* aCx, const nsAString& aMessageName,
                         JS::Handle<JS::Value> aObj,
                         JS::Handle<JSObject*> aObjects,
+                        nsIPrincipal* aPrincipal,
                         JS::Handle<JS::Value> aTransfers, ErrorResult& aError) {
     if (!mMessageManager) {
       aError.Throw(NS_ERROR_NOT_INITIALIZED);
       return;
     }
     mMessageManager->SendAsyncMessage(aCx, aMessageName, aObj, aObjects,
-                                      aTransfers, aError);
+                                      aPrincipal, aTransfers, aError);
   }
   already_AddRefed<ProcessMessageManager> GetProcessMessageManager(
       mozilla::ErrorResult& aError) {
@@ -87,29 +88,30 @@ class MessageManagerGlobal {
   // SyncMessageSender
   void SendSyncMessage(JSContext* aCx, const nsAString& aMessageName,
                        JS::Handle<JS::Value> aObj,
-                       JS::Handle<JSObject*> aObjects,
+                       JS::Handle<JSObject*> aObjects, nsIPrincipal* aPrincipal,
                        nsTArray<JS::Value>& aResult, ErrorResult& aError) {
     if (!mMessageManager) {
       aError.Throw(NS_ERROR_NOT_INITIALIZED);
       return;
     }
-    mMessageManager->SendSyncMessage(aCx, aMessageName, aObj, aObjects, aResult,
-                                     aError);
+    mMessageManager->SendSyncMessage(aCx, aMessageName, aObj, aObjects,
+                                     aPrincipal, aResult, aError);
   }
   void SendRpcMessage(JSContext* aCx, const nsAString& aMessageName,
                       JS::Handle<JS::Value> aObj,
-                      JS::Handle<JSObject*> aObjects,
+                      JS::Handle<JSObject*> aObjects, nsIPrincipal* aPrincipal,
                       nsTArray<JS::Value>& aResult, ErrorResult& aError) {
     if (!mMessageManager) {
       aError.Throw(NS_ERROR_NOT_INITIALIZED);
       return;
     }
-    mMessageManager->SendRpcMessage(aCx, aMessageName, aObj, aObjects, aResult,
-                                    aError);
+    mMessageManager->SendRpcMessage(aCx, aMessageName, aObj, aObjects,
+                                    aPrincipal, aResult, aError);
   }
 
   // MessageManagerGlobal
   void Dump(const nsAString& aStr);
+  void PrivateNoteIntentionalCrash(ErrorResult& aError);
   void Atob(const nsAString& aAsciiString, nsAString& aBase64Data,
             ErrorResult& aError);
   void Btoa(const nsAString& aBase64Data, nsAString& aAsciiString,
diff --git a/dom/base/nsFrameLoader.cpp b/dom/base/nsFrameLoader.cpp
index b5590ee02936..5f4c2986fbe6 100644
--- a/dom/base/nsFrameLoader.cpp
+++ b/dom/base/nsFrameLoader.cpp
@@ -236,30 +236,25 @@ static void GetFrameName(Element* aOwnerContent, nsAString& aFrameName) {
 // manner, they are no longer handled by typeContent and typeChrome. Instead,
 // the actual BrowsingContext tree is broken at these edges.
 static bool IsTopContent(BrowsingContext* aParent, Element* aOwner) {
-  if (XRE_IsContentProcess()) {
-    return false;
-  }
-
-  // If we have a (deprecated) mozbrowser element, we want to start a new
-  // BrowsingContext tree regardless of whether the parent is chrome or content.
   nsCOMPtr<nsIMozBrowserFrame> mozbrowser = aOwner->GetAsMozBrowserFrame();
-  if (mozbrowser && mozbrowser->GetReallyIsBrowser()) {
-    return true;
-  }
 
   if (aParent->IsContent()) {
     // If we're already in content, we may still want to create a new
-    // BrowsingContext tree if our element is a xul browser element with a
-    // `remote="true"` marker.
-    return aOwner->IsXULElement() &&
-           aOwner->AttrValueIs(kNameSpaceID_None, nsGkAtoms::remote,
-                               nsGkAtoms::_true, eCaseMatters);
+    // BrowsingContext tree if our element is either:
+    //  a) a real <iframe mozbrowser> frame, or
+    //  b) a xul browser element with a `remote="true"` marker.
+    return (mozbrowser && mozbrowser->GetReallyIsBrowser()) ||
+           (aOwner->IsXULElement() &&
+            aOwner->AttrValueIs(kNameSpaceID_None, nsGkAtoms::remote,
+                                nsGkAtoms::_true, eCaseMatters));
   }
 
-  // If we're in a chrome context, we want to start a new tree if we are an
-  // element with a `type="content"` marker.
-  return aOwner->AttrValueIs(kNameSpaceID_None, TypeAttrName(aOwner),
-                             nsGkAtoms::content, eIgnoreCase);
+  // If we're in a chrome context, we want to start a new tree if:
+  //  a) we have any mozbrowser frame (even if disabled), or
+  //  b) we are an element with a `type="content"` marker.
+  return (mozbrowser && mozbrowser->GetMozbrowser()) ||
+         (aOwner->AttrValueIs(kNameSpaceID_None, TypeAttrName(aOwner),
+                              nsGkAtoms::content, eIgnoreCase));
 }
 
 static already_AddRefed<BrowsingContext> CreateBrowsingContext(
@@ -308,8 +303,19 @@ static already_AddRefed<BrowsingContext> CreateBrowsingContext(
   // for the BrowsingContext, and cause no end of trouble.
   if (IsTopContent(parentContext, aOwner)) {
     // Create toplevel content without a parent & as Type::Content.
-    return BrowsingContext::CreateDetached(nullptr, opener, frameName,
-                                           BrowsingContext::Type::Content);
+    RefPtr<BrowsingContext> bc = BrowsingContext::CreateDetached(
+        nullptr, opener, frameName, BrowsingContext::Type::Content);
+
+    // If this is a mozbrowser frame, pretend it's windowless so that it gets
+    // ownership of its BrowsingContext even though it's a top-level content
+    // frame. This is horrible, but will fortunately go away soon.
+    if (nsCOMPtr<nsIMozBrowserFrame> mozbrowser =
+            aOwner->GetAsMozBrowserFrame()) {
+      if (mozbrowser->GetReallyIsBrowser()) {
+        bc->SetWindowless();
+      }
+    }
+    return bc.forget();
   }
 
   MOZ_ASSERT(!aOpenWindowInfo,
@@ -2139,9 +2145,13 @@ nsresult nsFrameLoader::MaybeCreateDocShell() {
     NS_ENSURE_SUCCESS(rv, rv);
   }
 
+  if (OwnerIsMozBrowserFrame()) {
+    docShell->SetFrameType(nsIDocShell::FRAME_TYPE_BROWSER);
+  }
+
   // Apply sandbox flags even if our owner is not an iframe, as this copies
   // flags from our owning content's owning document.
-  // Note: ApplySandboxFlags should be called after docShell->SetIsFrame
+  // Note: ApplySandboxFlags should be called after docShell->SetFrameType
   // because we need to get the correct presentation URL in ApplySandboxFlags.
   uint32_t sandboxFlags = 0;
   HTMLIFrameElement* iframe = HTMLIFrameElement::FromNode(mOwnerContent);
@@ -2156,6 +2166,10 @@ nsresult nsFrameLoader::MaybeCreateDocShell() {
     if (mOwnerContent->GetAttr(kNameSpaceID_None, nsGkAtoms::name, name)) {
       docShell->SetName(name);
     }
+    docShell->SetFullscreenAllowed(
+        mOwnerContent->HasAttr(kNameSpaceID_None, nsGkAtoms::allowfullscreen) ||
+        mOwnerContent->HasAttr(kNameSpaceID_None,
+                               nsGkAtoms::mozallowfullscreen));
   }
 
   // Typically there will be a window, however for some cases such as printing
@@ -2163,7 +2177,8 @@ nsresult nsFrameLoader::MaybeCreateDocShell() {
   // that the window exists to ensure we don't try to gather ancestors for
   // those cases.
   nsCOMPtr<nsPIDOMWindowOuter> win = doc->GetWindow();
-  if (parentDocShell->ItemType() == docShell->ItemType() &&
+  if (!docShell->GetIsMozBrowser() &&
+      parentDocShell->ItemType() == docShell->ItemType() &&
       !doc->IsStaticDocument() && win) {
     // Propagate through the ancestor principals.
     nsTArray<nsCOMPtr<nsIPrincipal>> ancestorPrincipals;
@@ -2804,7 +2819,8 @@ class nsAsyncMessageToChild : public nsSameProcessAsyncMessageBase,
 nsresult nsFrameLoader::DoSendAsyncMessage(JSContext* aCx,
                                            const nsAString& aMessage,
                                            StructuredCloneData& aData,
-                                           JS::Handle<JSObject*> aCpows) {
+                                           JS::Handle<JSObject*> aCpows,
+                                           nsIPrincipal* aPrincipal) {
   auto* browserParent = GetBrowserParent();
   if (browserParent) {
     ClonedMessageData data;
@@ -2818,7 +2834,8 @@ nsresult nsFrameLoader::DoSendAsyncMessage(JSContext* aCx,
     if (aCpows && (!mgr || !mgr->Wrap(aCx, aCpows, &cpows))) {
       return NS_ERROR_UNEXPECTED;
     }
-    if (browserParent->SendAsyncMessage(nsString(aMessage), cpows, data)) {
+    if (browserParent->SendAsyncMessage(nsString(aMessage), cpows, aPrincipal,
+                                        data)) {
       return NS_OK;
     } else {
       return NS_ERROR_UNEXPECTED;
@@ -2829,7 +2846,7 @@ nsresult nsFrameLoader::DoSendAsyncMessage(JSContext* aCx,
     JS::RootingContext* rcx = JS::RootingContext::get(aCx);
     RefPtr<nsAsyncMessageToChild> ev =
         new nsAsyncMessageToChild(rcx, aCpows, this);
-    nsresult rv = ev->Init(aMessage, aData);
+    nsresult rv = ev->Init(aMessage, aData, aPrincipal);
     if (NS_FAILED(rv)) {
       return rv;
     }
@@ -3329,9 +3346,9 @@ nsresult nsFrameLoader::GetNewTabContext(MutableTabContext* aTabContext,
 
   uint32_t maxTouchPoints = BrowserParent::GetMaxTouchPoints(mOwnerContent);
 
-  bool tabContextUpdated =
-      aTabContext->SetTabContext(chromeOuterWindowID, showFocusRings, attrs,
-                                 presentationURLStr, maxTouchPoints);
+  bool tabContextUpdated = aTabContext->SetTabContext(
+      OwnerIsMozBrowserFrame(), chromeOuterWindowID, showFocusRings, attrs,
+      presentationURLStr, maxTouchPoints);
   NS_ENSURE_STATE(tabContextUpdated);
 
   return NS_OK;
diff --git a/dom/base/nsFrameLoader.h b/dom/base/nsFrameLoader.h
index 419055f12763..cb7984daba61 100644
--- a/dom/base/nsFrameLoader.h
+++ b/dom/base/nsFrameLoader.h
@@ -256,7 +256,7 @@ class nsFrameLoader final : public nsStubMutationObserver,
   virtual nsresult DoSendAsyncMessage(
       JSContext* aCx, const nsAString& aMessage,
       mozilla::dom::ipc::StructuredCloneData& aData,
-      JS::Handle<JSObject*> aCpows) override;
+      JS::Handle<JSObject*> aCpows, nsIPrincipal* aPrincipal) override;
 
   /**
    * Called from the layout frame associated with this frame loader;
diff --git a/dom/base/nsFrameMessageManager.cpp b/dom/base/nsFrameMessageManager.cpp
index 9689896a7fd0..1b805fc6c48f 100644
--- a/dom/base/nsFrameMessageManager.cpp
+++ b/dom/base/nsFrameMessageManager.cpp
@@ -446,8 +446,8 @@ static bool AllowMessage(size_t aDataLength, const nsAString& aMessageName) {
 
 void nsFrameMessageManager::SendMessage(
     JSContext* aCx, const nsAString& aMessageName, JS::Handle<JS::Value> aObj,
-    JS::Handle<JSObject*> aObjects, bool aIsSync, nsTArray<JS::Value>& aResult,
-    ErrorResult& aError) {
+    JS::Handle<JSObject*> aObjects, nsIPrincipal* aPrincipal, bool aIsSync,
+    nsTArray<JS::Value>& aResult, ErrorResult& aError) {
   NS_ASSERTION(!IsGlobal(), "Should not call SendSyncMessage in chrome");
   NS_ASSERTION(!IsBroadcaster(), "Should not call SendSyncMessage in chrome");
   NS_ASSERTION(!GetParentManager(),
@@ -491,7 +491,7 @@ void nsFrameMessageManager::SendMessage(
   TimeStamp start = TimeStamp::Now();
   sSendingSyncMessage |= aIsSync;
   bool ok = mCallback->DoSendBlockingMessage(aCx, aMessageName, data, aObjects,
-                                             &retval, aIsSync);
+                                             aPrincipal, &retval, aIsSync);
   if (aIsSync) {
     sSendingSyncMessage = false;
   }
@@ -526,12 +526,12 @@ void nsFrameMessageManager::SendMessage(
 
 nsresult nsFrameMessageManager::DispatchAsyncMessageInternal(
     JSContext* aCx, const nsAString& aMessage, StructuredCloneData& aData,
-    JS::Handle<JSObject*> aCpows) {
+    JS::Handle<JSObject*> aCpows, nsIPrincipal* aPrincipal) {
   if (mIsBroadcaster) {
     uint32_t len = mChildManagers.Length();
     for (uint32_t i = 0; i < len; ++i) {
       mChildManagers[i]->DispatchAsyncMessageInternal(aCx, aMessage, aData,
-                                                      aCpows);
+                                                      aCpows, aPrincipal);
     }
     return NS_OK;
   }
@@ -540,7 +540,8 @@ nsresult nsFrameMessageManager::DispatchAsyncMessageInternal(
     return NS_ERROR_NOT_INITIALIZED;
   }
 
-  nsresult rv = mCallback->DoSendAsyncMessage(aCx, aMessage, aData, aCpows);
+  nsresult rv =
+      mCallback->DoSendAsyncMessage(aCx, aMessage, aData, aCpows, aPrincipal);
   if (NS_FAILED(rv)) {
     return rv;
   }
@@ -549,8 +550,8 @@ nsresult nsFrameMessageManager::DispatchAsyncMessageInternal(
 
 void nsFrameMessageManager::DispatchAsyncMessage(
     JSContext* aCx, const nsAString& aMessageName, JS::Handle<JS::Value> aObj,
-    JS::Handle<JSObject*> aObjects, JS::Handle<JS::Value> aTransfers,
-    ErrorResult& aError) {
+    JS::Handle<JSObject*> aObjects, nsIPrincipal* aPrincipal,
+    JS::Handle<JS::Value> aTransfers, ErrorResult& aError) {
   StructuredCloneData data;
   if (!aObj.isUndefined() &&
       !GetParamsForMessage(aCx, aObj, aTransfers, data)) {
@@ -569,7 +570,8 @@ void nsFrameMessageManager::DispatchAsyncMessage(
     return;
   }
 
-  aError = DispatchAsyncMessageInternal(aCx, aMessageName, data, aObjects);
+  aError = DispatchAsyncMessageInternal(aCx, aMessageName, data, aObjects,
+                                        aPrincipal);
 }
 
 class MMListenerRemover {
@@ -594,8 +596,8 @@ class MMListenerRemover {
 void nsFrameMessageManager::ReceiveMessage(
     nsISupports* aTarget, nsFrameLoader* aTargetFrameLoader, bool aTargetClosed,
     const nsAString& aMessage, bool aIsSync, StructuredCloneData* aCloneData,
-    mozilla::jsipc::CpowHolder* aCpows, nsTArray<StructuredCloneData>* aRetVal,
-    ErrorResult& aError) {
+    mozilla::jsipc::CpowHolder* aCpows, nsIPrincipal* aPrincipal,
+    nsTArray<StructuredCloneData>* aRetVal, ErrorResult& aError) {
   MOZ_ASSERT(aTarget);
 
   nsAutoTObserverArray<nsMessageListenerInfo, 1>* listeners =
@@ -694,6 +696,7 @@ void nsFrameMessageManager::ReceiveMessage(
       }
 
       argument.mName = aMessage;
+      argument.mPrincipal = aPrincipal;
       argument.mSync = aIsSync;
       argument.mTarget = aTarget;
       if (aTargetFrameLoader) {
@@ -801,7 +804,7 @@ void nsFrameMessageManager::ReceiveMessage(
   if (kungFuDeathGrip) {
     kungFuDeathGrip->ReceiveMessage(aTarget, aTargetFrameLoader, aTargetClosed,
                                     aMessage, aIsSync, aCloneData, aCpows,
-                                    aRetVal, aError);
+                                    aPrincipal, aRetVal, aError);
   }
 }
 
@@ -1380,12 +1383,13 @@ class SameParentProcessMessageManagerCallback : public MessageManagerCallback {
 
   nsresult DoSendAsyncMessage(JSContext* aCx, const nsAString& aMessage,
                               StructuredCloneData& aData,
-                              JS::Handle<JSObject*> aCpows) override {
+                              JS::Handle<JSObject*> aCpows,
+                              nsIPrincipal* aPrincipal) override {
     JS::RootingContext* rcx = JS::RootingContext::get(aCx);
     RefPtr<nsAsyncMessageToSameProcessChild> ev =
         new nsAsyncMessageToSameProcessChild(rcx, aCpows);
 
-    nsresult rv = ev->Init(aMessage, aData);
+    nsresult rv = ev->Init(aMessage, aData, aPrincipal);
     if (NS_FAILED(rv)) {
       return rv;
     }
@@ -1412,6 +1416,7 @@ class ChildProcessMessageManagerCallback : public MessageManagerCallback {
   bool DoSendBlockingMessage(JSContext* aCx, const nsAString& aMessage,
                              StructuredCloneData& aData,
                              JS::Handle<JSObject*> aCpows,
+                             nsIPrincipal* aPrincipal,
                              nsTArray<StructuredCloneData>* aRetVal,
                              bool aIsSync) override {
     mozilla::dom::ContentChild* cc = mozilla::dom::ContentChild::GetSingleton();
@@ -1428,15 +1433,16 @@ class ChildProcessMessageManagerCallback : public MessageManagerCallback {
     }
     if (aIsSync) {
       return cc->SendSyncMessage(PromiseFlatString(aMessage), data, cpows,
-                                 aRetVal);
+                                 IPC::Principal(aPrincipal), aRetVal);
     }
     return cc->SendRpcMessage(PromiseFlatString(aMessage), data, cpows,
-                              aRetVal);
+                              IPC::Principal(aPrincipal), aRetVal);
   }
 
   nsresult DoSendAsyncMessage(JSContext* aCx, const nsAString& aMessage,
                               StructuredCloneData& aData,
-                              JS::Handle<JSObject*> aCpows) override {
+                              JS::Handle<JSObject*> aCpows,
+                              nsIPrincipal* aPrincipal) override {
     mozilla::dom::ContentChild* cc = mozilla::dom::ContentChild::GetSingleton();
     if (!cc) {
       return NS_OK;
@@ -1449,7 +1455,8 @@ class ChildProcessMessageManagerCallback : public MessageManagerCallback {
     if (aCpows && !cc->GetCPOWManager()->Wrap(aCx, aCpows, &cpows)) {
       return NS_ERROR_UNEXPECTED;
     }
-    if (!cc->SendAsyncMessage(PromiseFlatString(aMessage), cpows, data)) {
+    if (!cc->SendAsyncMessage(PromiseFlatString(aMessage), cpows,
+                              IPC::Principal(aPrincipal), data)) {
       return NS_ERROR_UNEXPECTED;
     }
 
@@ -1487,6 +1494,7 @@ class SameChildProcessMessageManagerCallback : public MessageManagerCallback {
   bool DoSendBlockingMessage(JSContext* aCx, const nsAString& aMessage,
                              StructuredCloneData& aData,
                              JS::Handle<JSObject*> aCpows,
+                             nsIPrincipal* aPrincipal,
                              nsTArray<StructuredCloneData>* aRetVal,
                              bool aIsSync) override {
     SameProcessMessageQueue* queue = SameProcessMessageQueue::Get();
@@ -1496,20 +1504,21 @@ class SameChildProcessMessageManagerCallback : public MessageManagerCallback {
       SameProcessCpowHolder cpows(JS::RootingContext::get(aCx), aCpows);
       RefPtr<nsFrameMessageManager> ppm =
           nsFrameMessageManager::sSameProcessParentManager;
-      ppm->ReceiveMessage(ppm, nullptr, aMessage, true, &aData, &cpows, aRetVal,
-                          IgnoreErrors());
+      ppm->ReceiveMessage(ppm, nullptr, aMessage, true, &aData, &cpows,
+                          aPrincipal, aRetVal, IgnoreErrors());
     }
     return true;
   }
 
   nsresult DoSendAsyncMessage(JSContext* aCx, const nsAString& aMessage,
                               StructuredCloneData& aData,
-                              JS::Handle<JSObject*> aCpows) override {
+                              JS::Handle<JSObject*> aCpows,
+                              nsIPrincipal* aPrincipal) override {
     SameProcessMessageQueue* queue = SameProcessMessageQueue::Get();
     JS::RootingContext* rcx = JS::RootingContext::get(aCx);
     RefPtr<nsAsyncMessageToSameProcessParent> ev =
         new nsAsyncMessageToSameProcessParent(rcx, aCpows);
-    nsresult rv = ev->Init(aMessage, aData);
+    nsresult rv = ev->Init(aMessage, aData, aPrincipal);
 
     if (NS_FAILED(rv)) {
       return rv;
@@ -1603,7 +1612,8 @@ nsSameProcessAsyncMessageBase::nsSameProcessAsyncMessageBase(
 }
 
 nsresult nsSameProcessAsyncMessageBase::Init(const nsAString& aMessage,
-                                             StructuredCloneData& aData) {
+                                             StructuredCloneData& aData,
+                                             nsIPrincipal* aPrincipal) {
   if (!mData.Copy(aData)) {
     Telemetry::Accumulate(Telemetry::IPC_SAME_PROCESS_MESSAGE_COPY_OOM_KB,
                           aData.DataLength());
@@ -1611,6 +1621,7 @@ nsresult nsSameProcessAsyncMessageBase::Init(const nsAString& aMessage,
   }
 
   mMessage = aMessage;
+  mPrincipal = aPrincipal;
 #ifdef DEBUG
   mCalledInit = true;
 #endif
@@ -1628,6 +1639,6 @@ void nsSameProcessAsyncMessageBase::ReceiveMessage(
 
     RefPtr<nsFrameMessageManager> mm = aManager;
     mm->ReceiveMessage(aTarget, aTargetFrameLoader, mMessage, false, &mData,
-                       &cpows, nullptr, IgnoreErrors());
+                       &cpows, mPrincipal, nullptr, IgnoreErrors());
   }
 }
diff --git a/dom/base/nsFrameMessageManager.h b/dom/base/nsFrameMessageManager.h
index e4d8a65e0268..777987ae54d5 100644
--- a/dom/base/nsFrameMessageManager.h
+++ b/dom/base/nsFrameMessageManager.h
@@ -87,6 +87,7 @@ class MessageManagerCallback {
   virtual bool DoSendBlockingMessage(JSContext* aCx, const nsAString& aMessage,
                                      StructuredCloneData& aData,
                                      JS::Handle<JSObject*> aCpows,
+                                     nsIPrincipal* aPrincipal,
                                      nsTArray<StructuredCloneData>* aRetVal,
                                      bool aIsSync) {
     return true;
@@ -94,7 +95,8 @@ class MessageManagerCallback {
 
   virtual nsresult DoSendAsyncMessage(JSContext* aCx, const nsAString& aMessage,
                                       StructuredCloneData& aData,
-                                      JS::Handle<JSObject*> aCpows) {
+                                      JS::Handle<JSObject*> aCpows,
+                                      nsIPrincipal* aPrincipal) {
     return NS_OK;
   }
 
@@ -191,9 +193,11 @@ class nsFrameMessageManager : public nsIMessageSender {
   void SendAsyncMessage(JSContext* aCx, const nsAString& aMessageName,
                         JS::Handle<JS::Value> aObj,
                         JS::Handle<JSObject*> aObjects,
+                        nsIPrincipal* aPrincipal,
                         JS::Handle<JS::Value> aTransfers,
                         mozilla::ErrorResult& aError) {
-    DispatchAsyncMessage(aCx, aMessageName, aObj, aObjects, aTransfers, aError);
+    DispatchAsyncMessage(aCx, aMessageName, aObj, aObjects, aPrincipal,
+                         aTransfers, aError);
   }
   already_AddRefed<mozilla::dom::ProcessMessageManager>
   GetProcessMessageManager(mozilla::ErrorResult& aError);
@@ -203,17 +207,19 @@ class nsFrameMessageManager : public nsIMessageSender {
   // SyncMessageSender
   void SendSyncMessage(JSContext* aCx, const nsAString& aMessageName,
                        JS::Handle<JS::Value> aObj,
-                       JS::Handle<JSObject*> aObjects,
+                       JS::Handle<JSObject*> aObjects, nsIPrincipal* aPrincipal,
                        nsTArray<JS::Value>& aResult,
                        mozilla::ErrorResult& aError) {
-    SendMessage(aCx, aMessageName, aObj, aObjects, true, aResult, aError);
+    SendMessage(aCx, aMessageName, aObj, aObjects, aPrincipal, true, aResult,
+                aError);
   }
   void SendRpcMessage(JSContext* aCx, const nsAString& aMessageName,
                       JS::Handle<JS::Value> aObj,
-                      JS::Handle<JSObject*> aObjects,
+                      JS::Handle<JSObject*> aObjects, nsIPrincipal* aPrincipal,
                       nsTArray<JS::Value>& aResult,
                       mozilla::ErrorResult& aError) {
-    SendMessage(aCx, aMessageName, aObj, aObjects, false, aResult, aError);
+    SendMessage(aCx, aMessageName, aObj, aObjects, aPrincipal, false, aResult,
+                aError);
   }
 
   // GlobalProcessScriptLoader
@@ -232,10 +238,11 @@ class nsFrameMessageManager : public nsIMessageSender {
                       const nsAString& aMessage, bool aIsSync,
                       StructuredCloneData* aCloneData,
                       mozilla::jsipc::CpowHolder* aCpows,
+                      nsIPrincipal* aPrincipal,
                       nsTArray<StructuredCloneData>* aRetVal,
                       mozilla::ErrorResult& aError) {
     ReceiveMessage(aTarget, aTargetFrameLoader, mClosed, aMessage, aIsSync,
-                   aCloneData, aCpows, aRetVal, aError);
+                   aCloneData, aCpows, aPrincipal, aRetVal, aError);
   }
 
   void Disconnect(bool aRemoveFromParent = true);
@@ -248,7 +255,8 @@ class nsFrameMessageManager : public nsIMessageSender {
   nsresult DispatchAsyncMessageInternal(JSContext* aCx,
                                         const nsAString& aMessage,
                                         StructuredCloneData& aData,
-                                        JS::Handle<JSObject*> aCpows);
+                                        JS::Handle<JSObject*> aCpows,
+                                        nsIPrincipal* aPrincipal);
   bool IsGlobal() { return mGlobal; }
   bool IsBroadcaster() { return mIsBroadcaster; }
   bool IsChrome() { return mChrome; }
@@ -287,18 +295,20 @@ class nsFrameMessageManager : public nsIMessageSender {
   void DispatchAsyncMessage(JSContext* aCx, const nsAString& aMessageName,
                             JS::Handle<JS::Value> aObj,
                             JS::Handle<JSObject*> aObjects,
+                            nsIPrincipal* aPrincipal,
                             JS::Handle<JS::Value> aTransfers,
                             mozilla::ErrorResult& aError);
 
   void SendMessage(JSContext* aCx, const nsAString& aMessageName,
                    JS::Handle<JS::Value> aObj, JS::Handle<JSObject*> aObjects,
-                   bool aIsSync, nsTArray<JS::Value>& aResult,
-                   mozilla::ErrorResult& aError);
+                   nsIPrincipal* aPrincipal, bool aIsSync,
+                   nsTArray<JS::Value>& aResult, mozilla::ErrorResult& aError);
 
   void ReceiveMessage(nsISupports* aTarget, nsFrameLoader* aTargetFrameLoader,
                       bool aTargetClosed, const nsAString& aMessage,
                       bool aIsSync, StructuredCloneData* aCloneData,
                       mozilla::jsipc::CpowHolder* aCpows,
+                      nsIPrincipal* aPrincipal,
                       nsTArray<StructuredCloneData>* aRetVal,
                       mozilla::ErrorResult& aError);
 
@@ -366,7 +376,8 @@ class nsSameProcessAsyncMessageBase {
 
   nsSameProcessAsyncMessageBase(JS::RootingContext* aRootingCx,
                                 JS::Handle<JSObject*> aCpows);
-  nsresult Init(const nsAString& aMessage, StructuredCloneData& aData);
+  nsresult Init(const nsAString& aMessage, StructuredCloneData& aData,
+                nsIPrincipal* aPrincipal);
 
   void ReceiveMessage(nsISupports* aTarget, nsFrameLoader* aTargetFrameLoader,
                       nsFrameMessageManager* aManager);
@@ -377,6 +388,7 @@ class nsSameProcessAsyncMessageBase {
   nsString mMessage;
   StructuredCloneData mData;
   JS::PersistentRooted<JSObject*> mCpows;
+  nsCOMPtr<nsIPrincipal> mPrincipal;
 #ifdef DEBUG
   bool mCalledInit;
 #endif
@@ -419,6 +431,7 @@ class nsMessageManagerScriptExecutor {
   bool Init();
   void Trace(const TraceCallbacks& aCallbacks, void* aClosure);
   void Unlink();
+  nsCOMPtr<nsIPrincipal> mPrincipal;
   AutoTArray<JS::Heap<JSObject*>, 2> mAnonymousGlobalScopes;
 
   // Returns true if this is a process message manager. There should only be a
diff --git a/dom/base/nsGlobalWindowOuter.cpp b/dom/base/nsGlobalWindowOuter.cpp
index 4f4116e65fad..7fd4557159e8 100644
--- a/dom/base/nsGlobalWindowOuter.cpp
+++ b/dom/base/nsGlobalWindowOuter.cpp
@@ -3162,12 +3162,12 @@ nsPIDOMWindowOuter* nsGlobalWindowOuter::GetInProcessScriptableParent() {
     return nullptr;
   }
 
-  if (BrowsingContext* parentBC = GetBrowsingContext()->GetParent()) {
-    if (nsCOMPtr<nsPIDOMWindowOuter> parent = parentBC->GetDOMWindow()) {
-      return parent;
-    }
+  if (mDocShell->GetIsMozBrowser()) {
+    return this;
   }
-  return this;
+
+  nsCOMPtr<nsPIDOMWindowOuter> parent = GetInProcessParent();
+  return parent;
 }
 
 /**
@@ -3340,6 +3340,13 @@ already_AddRefed<nsPIDOMWindowOuter> nsGlobalWindowOuter::GetContentInternal(
     return content.forget();
   }
 
+  // If we're contained in <iframe mozbrowser>, then GetContent is the same as
+  // window.top.
+  if (mDocShell && mDocShell->GetIsInMozBrowser()) {
+    nsCOMPtr<nsPIDOMWindowOuter> domWindow(GetInProcessScriptableTop());
+    return domWindow.forget();
+  }
+
   nsCOMPtr<nsIDocShellTreeItem> primaryContent;
   if (aCallerType != CallerType::System) {
     if (mDoc) {
@@ -5374,6 +5381,19 @@ nsresult nsGlobalWindowOuter::MoveBy(int32_t aXDif, int32_t aYDif) {
 void nsGlobalWindowOuter::ResizeToOuter(int32_t aWidth, int32_t aHeight,
                                         CallerType aCallerType,
                                         ErrorResult& aError) {
+  /*
+   * If caller is a browser-element then dispatch a resize event to
+   * the embedder.
+   */
+  if (mDocShell && mDocShell->GetIsMozBrowser()) {
+    CSSIntSize size(aWidth, aHeight);
+    if (!DispatchResizeEvent(size)) {
+      // The embedder chose to prevent the default action for this
+      // event, so let's not resize this window after all...
+      return;
+    }
+  }
+
   /*
    * If caller is not chrome and the user has not explicitly exempted the site,
    * prevent window.resizeTo() by exiting early
@@ -5402,6 +5422,26 @@ void nsGlobalWindowOuter::ResizeToOuter(int32_t aWidth, int32_t aHeight,
 void nsGlobalWindowOuter::ResizeByOuter(int32_t aWidthDif, int32_t aHeightDif,
                                         CallerType aCallerType,
                                         ErrorResult& aError) {
+  /*
+   * If caller is a browser-element then dispatch a resize event to
+   * parent.
+   */
+  if (mDocShell && mDocShell->GetIsMozBrowser()) {
+    CSSIntSize size;
+    if (NS_FAILED(GetInnerSize(size))) {
+      return;
+    }
+
+    size.width += aWidthDif;
+    size.height += aHeightDif;
+
+    if (!DispatchResizeEvent(size)) {
+      // The embedder chose to prevent the default action for this
+      // event, so let's not resize this window after all...
+      return;
+    }
+  }
+
   /*
    * If caller is not chrome and the user has not explicitly exempted the site,
    * prevent window.resizeBy() by exiting early
@@ -6069,7 +6109,8 @@ bool nsGlobalWindowOuter::CanClose() {
 }
 
 void nsGlobalWindowOuter::CloseOuter(bool aTrustedCaller) {
-  if (!mDocShell || IsInModalState() || IsFrame()) {
+  if (!mDocShell || IsInModalState() ||
+      (IsFrame() && !mDocShell->GetIsMozBrowser())) {
     // window.close() is called on a frame in a frameset, on a window
     // that's already closed, or on a window for which there's
     // currently a modal dialog open. Ignore such calls.
diff --git a/dom/base/test/chrome.ini b/dom/base/test/chrome.ini
index cb9b26db89c2..450b10db6281 100644
--- a/dom/base/test/chrome.ini
+++ b/dom/base/test/chrome.ini
@@ -13,6 +13,7 @@ support-files =
   file_script.js
   referrer_helper.js
   referrer_testserver.sjs
+  mozbrowser_api_utils.js
   !/image/test/mochitest/shaver.png
 
 [test_anonymousContent_xul_window.xhtml]
@@ -25,7 +26,9 @@ support-files =
 [test_anchor_target_blank_referrer.html]
 [test_domrequesthelper.xhtml]
 [test_fragment_sanitization.xhtml]
+[test_messagemanager_principal.html]
 [test_messagemanager_send_principal.html]
+[test_mozbrowser_apis_allowed.html]
 [test_navigator_resolve_identity_xrays.xhtml]
 support-files = file_navigator_resolve_identity_xrays.xhtml
 [test_sandboxed_blob_uri.html]
diff --git a/dom/base/test/chrome/window_swapFrameLoaders.xhtml b/dom/base/test/chrome/window_swapFrameLoaders.xhtml
index 1b349c21a4f5..ff3618a6a899 100644
--- a/dom/base/test/chrome/window_swapFrameLoaders.xhtml
+++ b/dom/base/test/chrome/window_swapFrameLoaders.xhtml
@@ -99,7 +99,8 @@ Test swapFrameLoaders with different frame types and remoteness
 
   add_task(async function() {
     await SpecialPowers.pushPrefEnv(
-      { "set": [["network.disable.ipc.security", true]] });
+      { "set": [["dom.mozBrowserFramesEnabled", true],
+                ["network.disable.ipc.security", true]] });
   });
 
   add_task(async function() {
@@ -220,6 +221,35 @@ Test swapFrameLoaders with different frame types and remoteness
         is(pongB, "A", "Frame B message manager acquired after swap gets reply A after swap");
       }
 
+      // Verify browser API frame scripts destroyed if swapped out of browser frame
+      if (frameA.hasAttribute("mozbrowser") != frameB.hasAttribute("mozbrowser")) {
+        let mmA = frameA.frameLoader.messageManager;
+        let mmB = frameB.frameLoader.messageManager;
+
+        let inflightA = once(mmA, "check-browser-api");
+        let inflightB = once(mmB, "check-browser-api");
+
+        info("Check browser API for frame A");
+        mmA.sendAsyncMessage("check-browser-api");
+        let [ { data: apiA } ] = await inflightA;
+        if (frameA.hasAttribute("mozbrowser")) {
+          ok(apiA.exists && apiA.running, "Frame A browser API exists and is running");
+        } else {
+          ok(apiA.exists && !apiA.running, "Frame A browser API did exist but is now destroyed");
+        }
+
+        info("Check browser API for frame B");
+        mmB.sendAsyncMessage("check-browser-api");
+        let [ { data: apiB } ] = await inflightB;
+        if (frameB.hasAttribute("mozbrowser")) {
+          ok(apiB.exists && apiB.running, "Frame B browser API exists and is running");
+        } else {
+          ok(apiB.exists && !apiB.running, "Frame B browser API did exist but is now destroyed");
+        }
+      } else {
+        info("Frames have matching mozbrowser state, skipping browser API destruction check");
+      }
+
       frameA.remove();
       frameB.remove();
     }
diff --git a/dom/base/test/iframe_main_bug1022229.html b/dom/base/test/iframe_main_bug1022229.html
index c89a8c9a9df5..4a725f925595 100644
--- a/dom/base/test/iframe_main_bug1022229.html
+++ b/dom/base/test/iframe_main_bug1022229.html
@@ -2,6 +2,13 @@
 <html>
 <head>
 <script>
+  // Uncomment this definition of SimpleTest (and comment out the one below) to
+  // debug in mozBrowser mode.
+  /*
+  var SimpleTest = { ok: function(c, m) { dump(m + ": " + c + "\n"); },
+                     info: function(m) { dump(m + "\n"); },
+                     finish: function() { dump("Test done\n");} };
+  */
   var SimpleTest = parent.SimpleTest;
 
   var ok = SimpleTest.ok;
diff --git a/dom/base/test/mochitest.ini b/dom/base/test/mochitest.ini
index 6d53d6be6934..f9e532fc0fce 100644
--- a/dom/base/test/mochitest.ini
+++ b/dom/base/test/mochitest.ini
@@ -218,6 +218,7 @@ support-files =
   file_bug1250148.sjs
   file_bug1268962.sjs
   iframe_meta_refresh.sjs
+  mozbrowser_api_utils.js
   !/dom/security/test/cors/file_CrossSiteXHR_server.sjs
   !/image/test/mochitest/blue.png
   script_bug1238440.js
@@ -697,6 +698,7 @@ skip-if = !e10s # Track Bug 1281415
 [test_link_stylesheet.html]
 [test_location_href_unknown_protocol.html]
 support-files = file_location_href_unknown_protocol.html
+[test_messagemanager_targetchain.html]
 [test_meta_refresh_referrer.html]
 [test_meta_viewport0.html]
 [test_meta_viewport1.html]
@@ -745,6 +747,7 @@ support-files = file_location_href_unknown_protocol.html
 [test_meta_viewport_tiny_display_size.html]
 [test_meta_viewport_initial_scale_with_trailing_characters.html]
 [test_meta_viewport_width_with_trailing_characters.html]
+[test_mozbrowser_apis_blocked.html]
 [test_mozMatchesSelector.html]
 [test_mutationobserver_anonymous.html]
 [test_mutationobservers.html]
diff --git a/dom/base/test/mozbrowser_api_utils.js b/dom/base/test/mozbrowser_api_utils.js
new file mode 100644
index 000000000000..606489032ccc
--- /dev/null
+++ b/dom/base/test/mozbrowser_api_utils.js
@@ -0,0 +1,53 @@
+const FRAME_URL = "http://example.org/";
+
+const METHODS = {
+  sendMouseEvent: {},
+  goBack: {},
+  goForward: {},
+  reload: {},
+  stop: {},
+  getCanGoBack: {},
+  getCanGoForward: {},
+};
+
+const ATTRIBUTES = [];
+
+function once(target, eventName, useCapture = false) {
+  info(
+    "Waiting for event: '" + JSON.stringify(eventName) + "' on " + target + "."
+  );
+
+  return new Promise(resolve => {
+    for (let [add, remove] of [
+      ["addEventListener", "removeEventListener"],
+      ["addMessageListener", "removeMessageListener"],
+    ]) {
+      if (add in target && remove in target) {
+        eventName.forEach(evName => {
+          target[add](
+            evName,
+            function onEvent(...aArgs) {
+              info("Got event: '" + evName + "' on " + target + ".");
+              target[remove](evName, onEvent, useCapture);
+              resolve(aArgs);
+            },
+            useCapture
+          );
+        });
+        break;
+      }
+    }
+  });
+}
+
+async function loadFrame(attributes = {}) {
+  let iframe = document.createElement("iframe");
+  iframe.setAttribute("src", FRAME_URL);
+  for (let key in attributes) {
+    iframe.setAttribute(key, attributes[key]);
+  }
+  let loaded = once(iframe, ["load", "mozbrowserloadend"]);
+  document.body.appendChild(iframe);
+  await loaded;
+  return iframe;
+}
diff --git a/dom/base/test/test_bug1022229.html b/dom/base/test/test_bug1022229.html
index 7663cc22d0b1..ee0adb861e7e 100644
--- a/dom/base/test/test_bug1022229.html
+++ b/dom/base/test/test_bug1022229.html
@@ -11,11 +11,25 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=1022229
   <script type="application/javascript">
 
   /** Test for postMessage between sandboxed iframe and non-sandboxed window.
+      This test is particularly interesting on b2g where we're in a mozBrowser.
+
+      We set the test up with an extra iframe so that we can easily run it in
+      an artificial mozbrowser for desktop builds.
    **/
   SimpleTest.waitForExplicitFinish();
   function go() {
     var ifr = document.createElement('iframe');
 
+    /* Uncomment this chunk to run in a mozBrowser. Make sure to uncomment the
+       chunk in iframe_main as well. */
+    /*
+    SpecialPowers.Services.prefs.setBoolPref("dom.mozBrowserFramesEnabled", true);
+    SpecialPowers.Services.prefs.setBoolPref("network.disable.ipc.security", true);
+    SpecialPowers.Services.prefs.setBoolPref("dom.ipc.browser_frames.oop_by_default", false);
+    SpecialPowers.addPermission("browser", true, document);
+    SpecialPowers.wrap(ifr).mozbrowser = true;
+    */
+
     ifr.setAttribute('src', 'iframe_main_bug1022229.html');
     document.body.appendChild(ifr);
   }
diff --git a/dom/base/test/test_messagemanager_principal.html b/dom/base/test/test_messagemanager_principal.html
new file mode 100644
index 000000000000..0915485d2715
--- /dev/null
+++ b/dom/base/test/test_messagemanager_principal.html
@@ -0,0 +1,88 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test for Principal in MessageManager</title>
+  <script src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="chrome://mochikit/content/tests/SimpleTest/test.css"?>
+</head>
+<body>
+
+  <script type="application/javascript">
+    "use strict";
+
+    var permManager = Cc["@mozilla.org/permissionmanager;1"]
+                        .getService(Ci.nsIPermissionManager);
+
+    SimpleTest.waitForExplicitFinish();
+
+    const childFrameURL =
+      "data:text/html,<!DOCTYPE HTML><html><body></body></html>";
+
+    function childFrameScript() {
+      "use strict";
+
+      addMessageListener("test:ipcMessage", function(message) {
+        sendAsyncMessage(message.name, "principal: " + (message.principal ? "OK" : "KO"));
+
+        sendAsyncMessage(message.name, "principal.origin: " +
+                         ("origin" in message.principal ? "OK" : "KO"));
+
+        sendAsyncMessage(message.name, "principal.isInIsolatedMozBrowserElement: " +
+                         ("isInIsolatedMozBrowserElement" in message.principal ? "OK" : "KO"));
+
+        sendAsyncMessage(message.name, "DONE");
+      });
+    }
+
+    function runTests() {
+      ok("Browser prefs set.");
+
+      let iframe = document.createElement("iframe");
+      SpecialPowers.wrap(iframe).mozbrowser = true;
+      iframe.id = "iframe";
+      iframe.src = childFrameURL;
+
+      iframe.addEventListener("mozbrowserloadend", function() {
+        ok(true, "Got iframe load event.");
+
+        let mm = SpecialPowers.getBrowserFrameMessageManager(iframe);
+        mm.addMessageListener("test:ipcMessage", function(message) {
+          // We need to wrap to access message.json, and unwrap to do the
+          // identity check.
+          var msg = SpecialPowers.unwrap(SpecialPowers.wrap(message).json);
+          if (/OK$/.exec(msg)) {
+            ok(true, msg);
+          } else if(/KO$/.exec(msg)) {
+            ok(true, false);
+          } else if (/DONE/.exec(msg)) {
+            permManager.removeFromPrincipal(window.document.nodePrincipal, "browser",
+                                            Ci.nsIPermissionManager.ALLOW_ACTION);
+            SimpleTest.finish();
+          }
+        });
+        mm.loadFrameScript("data:,(" + childFrameScript.toString() + ")();",
+                           false);
+
+        mm.sendAsyncMessage("test:ipcMessage", 42, null, window.document.nodePrincipal);
+      });
+
+      document.body.appendChild(iframe);
+    }
+
+    addEventListener("load", function() {
+      info("Got load event.");
+
+      permManager.addFromPrincipal(window.document.nodePrincipal, "browser",
+                                   Ci.nsIPermissionManager.ALLOW_ACTION);
+
+      SpecialPowers.pushPrefEnv({
+        "set": [
+          ["dom.mozBrowserFramesEnabled", true],
+          ["network.disable.ipc.security", true],
+          ["browser.pagethumbnails.capturing_disabled", true]
+        ]
+      }, runTests);
+    });
+  </script>
+</body>
+</html>
diff --git a/dom/base/test/test_messagemanager_send_principal.html b/dom/base/test/test_messagemanager_send_principal.html
index 2adb94a71a59..8e139357b9d7 100644
--- a/dom/base/test/test_messagemanager_send_principal.html
+++ b/dom/base/test/test_messagemanager_send_principal.html
@@ -28,6 +28,9 @@
 
         sendAsyncMessage("test:result", "principal.origin: " +
                          ("origin" in message.data ? "OK" : "KO"));
+
+        sendAsyncMessage("test:result", "principal.isInIsolatedMozBrowserElement: " +
+                         ("isInIsolatedMozBrowserElement" in message.data ? "OK" : "KO"));
       });
 
       addMessageListener("test:system", function(message) {
@@ -55,19 +58,18 @@
     function runTests() {
       ok("Browser prefs set.");
 
-      let iframe = document.createXULElement("browser");
-      iframe.setAttribute("type", "content");
-      iframe.setAttribute("forcemessagemanager", "true");
+      let iframe = document.createElement("iframe");
+      SpecialPowers.wrap(iframe).mozbrowser = true;
       iframe.id = "iframe";
       iframe.src = childFrameURL;
 
       let sb = new Cu.Sandbox(['http://foo.example.com', 'http://bar.example.com']);
       let ep = Cu.getObjectPrincipal(sb);
 
-      iframe.addEventListener("load", function() {
+      iframe.addEventListener("mozbrowserloadend", function() {
         ok(true, "Got iframe load event.");
 
-        let mm = iframe.messageManager;
+        let mm = SpecialPowers.getBrowserFrameMessageManager(iframe);
         mm.addMessageListener("test:result", function(message) {
           // We need to wrap to access message.json, and unwrap to do the
           // identity check.
@@ -77,6 +79,8 @@
           } else if(/KO$/.exec(msg)) {
             ok(true, false);
           } else if (/DONE/.exec(msg)) {
+            permManager.removeFromPrincipal(window.document.nodePrincipal, "browser",
+                                            Ci.nsIPermissionManager.ALLOW_ACTION);
             SimpleTest.finish();
           }
         });
@@ -102,8 +106,13 @@
     addEventListener("load", function() {
       info("Got load event.");
 
+      permManager.addFromPrincipal(window.document.nodePrincipal, "browser",
+                                   Ci.nsIPermissionManager.ALLOW_ACTION);
+
       SpecialPowers.pushPrefEnv({
         "set": [
+          ["dom.mozBrowserFramesEnabled", true],
+          ["network.disable.ipc.security", true],
           ["browser.pagethumbnails.capturing_disabled", true]
         ]
       }, runTests);
diff --git a/dom/base/test/test_messagemanager_targetchain.html b/dom/base/test/test_messagemanager_targetchain.html
new file mode 100644
index 000000000000..0be6fb1f7be8
--- /dev/null
+++ b/dom/base/test/test_messagemanager_targetchain.html
@@ -0,0 +1,121 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test for EventTarget chain of MessageManagers</title>
+  <script src="/tests/SimpleTest/SimpleTest.js">
+  </script>
+  <script src="/tests/SimpleTest/EventUtils.js">
+  </script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+  <script type="application/javascript">
+    "use strict";
+
+    SimpleTest.waitForExplicitFinish();
+
+    const browserFrameURL = "file_empty.html";
+    const contentFrameURL =
+      "data:text/html,<!DOCTYPE HTML><html><body><button id=\"target\">target</button></body></html>";
+
+    function frameScript() {
+      "use strict";
+      addEventListener("test-event", function (e) {
+        sendSyncMessage("test-event");
+      }, true);
+    }
+
+    function runTests() {
+      // messageIndex is incremented for each message/event received
+      let messageIndex = 0;
+
+      let iframe = document.createElement("iframe");
+      iframe.setAttribute("mozbrowser", true);
+      iframe.setAttribute("src", browserFrameURL);
+
+      iframe.addEventListener("mozbrowserloadend", function () {
+        info("First iframe loaded");
+        // First message manager
+        let mm = SpecialPowers.getBrowserFrameMessageManager(iframe);
+        mm.addMessageListener("test-event", function onEvent(message) {
+          is(messageIndex, 0,
+             "first mm should be the first one to receive the test event");
+          messageIndex++;
+        });
+        mm.loadFrameScript("data:,(" + frameScript.toString() + ")();", false);
+
+        // Document in the middle
+        let doc1 = SpecialPowers.wrap(iframe).contentDocument;
+        doc1.addEventListener("test-event", function (e) {
+          ok(false, "content document shouldn't receive test event from child");
+        }, true);
+
+        let iframe2 = doc1.createElement("iframe");
+        iframe2.setAttribute("mozbrowser", true);
+        iframe2.setAttribute("src", browserFrameURL);
+
+        iframe2.addEventListener("mozbrowserloadend", function () {
+          info("Second iframe loaded");
+          // Second message manager
+          let mm2 = SpecialPowers.getBrowserFrameMessageManager(iframe2);
+          mm2.addMessageListener("test-event", function onEvent(message) {
+            is(messageIndex, 1,
+               "second mm should be the second one to receive the test event");
+            messageIndex++;
+          });
+          mm2.loadFrameScript("data:,(" + frameScript.toString() +")();", false);
+
+          // Third is the regular iframe
+          let doc2 = SpecialPowers.wrap(iframe2).contentDocument;
+          let iframe3 = doc2.createElement("iframe");
+          iframe3.setAttribute("src", contentFrameURL);
+
+          iframe3.addEventListener("load", function (e) {
+            info("Third iframe loaded");
+            let doc3 = SpecialPowers.wrap(iframe3).contentDocument;
+            let target = doc3.getElementById("target");
+            target.addEventListener("test-event", function onEvent() {
+              is(messageIndex, 2,
+                 "target should be the last one to receive the test event");
+              messageIndex++;
+              SimpleTest.finish();
+            });
+
+            // Fire test event after load
+            SimpleTest.executeSoon(function () {
+              var event = new Event("test-event");
+              SpecialPowers.dispatchEvent(iframe3.contentWindow, target, event);
+            });
+          });
+          doc2.body.appendChild(iframe3);
+        });
+        doc1.body.appendChild(iframe2);
+      });
+      document.addEventListener("test-event", function (e) {
+        ok(false, "top document shouldn't receive test event from child");
+      }, true);
+      document.body.appendChild(iframe);
+    }
+
+    addEventListener("load", function() {
+      var principal = SpecialPowers.wrap(document).nodePrincipal;
+      SpecialPowers.pushPermissions([
+        { type: "browser", allow: 1, context: { url: principal.URI.spec,
+                                                originAttributes: {}}},
+        { type: "browser", allow: 1, context: { url: principal.URI.spec,
+                                                originAttributes: {
+                                                  inIsolatedMozBrowser: true }}}
+      ], () => {
+        SpecialPowers.pushPrefEnv({
+          set: [
+            ["dom.mozBrowserFramesEnabled", true],
+            ["network.disable.ipc.security", true],
+            ["dom.ipc.browser_frames.oop_by_default", false],
+          ]
+        }, runTests);
+      });
+    });
+  </script>
+</body>
+</html>
diff --git a/dom/base/test/test_mozbrowser_apis_allowed.html b/dom/base/test/test_mozbrowser_apis_allowed.html
new file mode 100644
index 000000000000..eca06e079b0e
--- /dev/null
+++ b/dom/base/test/test_mozbrowser_apis_allowed.html
@@ -0,0 +1,42 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Verify mozbrowser APIs are allowed with browser permission</title>
+  <script src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="mozbrowser_api_utils.js"></script>
+  <link rel="stylesheet" type="text/css" href="chrome://mochikit/content/tests/SimpleTest/test.css" />
+</head>
+
+<body>
+<script type="application/javascript">
+  add_task(async function() {
+    await SpecialPowers.pushPrefEnv(
+      { "set": [["dom.mozBrowserFramesEnabled", true],
+                ["network.disable.ipc.security", true]] });
+  });
+
+  add_task(async function() {
+    // Create <iframe mozbrowser>
+    let frame = await loadFrame({
+      mozbrowser: "true",
+      // FIXME: Bug 1270790
+      remote: true
+    });
+
+    // Verify that mozbrowser APIs are accessible
+    for (let method in METHODS) {
+      let { alwaysFails } = METHODS[method];
+      if (alwaysFails) {
+        ok(!(method in frame), `frame does not have method ${method}, ` +
+                               `needs more permissions`);
+      } else {
+        ok(method in frame, `frame has method ${method}`);
+      }
+    }
+    for (let attribute of ATTRIBUTES) {
+      ok(attribute in frame, `frame has attribute ${attribute}`);
+    }
+  });
+</script>
+</body>
+</html>
diff --git a/dom/base/test/test_mozbrowser_apis_blocked.html b/dom/base/test/test_mozbrowser_apis_blocked.html
new file mode 100644
index 000000000000..5cc2721f6484
--- /dev/null
+++ b/dom/base/test/test_mozbrowser_apis_blocked.html
@@ -0,0 +1,34 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Verify mozbrowser APIs are blocked without browser permission</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="mozbrowser_api_utils.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+
+<body>
+<script type="application/javascript">
+  add_task(async function() {
+    await SpecialPowers.pushPrefEnv(
+      { "set": [["dom.mozBrowserFramesEnabled", true],
+                ["network.disable.ipc.security", true]] });
+  });
+
+  add_task(async function() {
+    // Create <iframe mozbrowser>
+    let frame = await loadFrame({
+      mozbrowser: "true"
+    });
+
+    // Verify that mozbrowser APIs are not accessible
+    for (let method in METHODS) {
+      ok(!(method in frame), `frame does not have method ${method}`);
+    }
+    for (let attribute of ATTRIBUTES) {
+      ok(!(attribute in frame), `frame does not have attribute ${attribute}`);
+    }
+  });
+</script>
+</body>
+</html>
diff --git a/dom/browser-element/mochitest/.eslintrc.js b/dom/browser-element/mochitest/.eslintrc.js
new file mode 100644
index 000000000000..19d9df957ac9
--- /dev/null
+++ b/dom/browser-element/mochitest/.eslintrc.js
@@ -0,0 +1,5 @@
+"use strict";
+
+module.exports = {
+  extends: ["plugin:mozilla/chrome-test", "plugin:mozilla/mochitest-test"],
+};
diff --git a/dom/browser-element/mochitest/async.js b/dom/browser-element/mochitest/async.js
new file mode 100644
index 000000000000..dfbc3a0f2406
--- /dev/null
+++ b/dom/browser-element/mochitest/async.js
@@ -0,0 +1,76 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/*
+ * This is an approximate implementation of ES7's async-await pattern.
+ * see: https://github.com/tc39/ecmascript-asyncawait
+ *
+ * It allows for simple creation of async function and "tasks".
+ *
+ * For example:
+ *
+ *  var myThinger = {
+ *    doAsynThing: async(function*(url){
+ *      var result = yield fetch(url);
+ *      return process(result);
+ *    });
+ * }
+ *
+ * And Task-like things can be created as follows:
+ *
+ * var myTask = async(function*{
+ *   var result = yield fetch(url);
+ *   return result;
+ * });
+ * //returns a promise
+ *
+ * myTask().then(doSomethingElse);
+ *
+ */
+
+(function(exports) {
+  "use strict";
+  function async(func, self) {
+    return function asyncFunction() {
+      const functionArgs = Array.from(arguments);
+      return new Promise(function(resolve, reject) {
+        var gen;
+        if (typeof func !== "function") {
+          reject(new TypeError("Expected a Function."));
+        }
+        // not a generator, wrap it.
+        if (func.constructor.name !== "GeneratorFunction") {
+          gen = (function*() {
+            return func.apply(self, functionArgs);
+          })();
+        } else {
+          gen = func.apply(self, functionArgs);
+        }
+        try {
+          step(gen.next(undefined));
+        } catch (err) {
+          reject(err);
+        }
+
+        function step({ value, done }) {
+          if (done) {
+            return resolve(value);
+          }
+          if (value instanceof Promise) {
+            return value
+              .then(
+                result => step(gen.next(result)),
+                error => {
+                  step(gen.throw(error));
+                }
+              )
+              .catch(err => reject(err));
+          }
+          return step(gen.next(value));
+        }
+      });
+    };
+  }
+  exports.async = async;
+})(this || self);
diff --git a/dom/browser-element/mochitest/audio.ogg b/dom/browser-element/mochitest/audio.ogg
new file mode 100644
index 000000000000..44ab64f81153
Binary files /dev/null and b/dom/browser-element/mochitest/audio.ogg differ
diff --git a/dom/browser-element/mochitest/browserElementTestHelpers.js b/dom/browser-element/mochitest/browserElementTestHelpers.js
new file mode 100644
index 000000000000..05ed87740346
--- /dev/null
+++ b/dom/browser-element/mochitest/browserElementTestHelpers.js
@@ -0,0 +1,300 @@
+/* Any copyright is dedicated to the public domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+// Helpers for managing the browser frame preferences.
+"use strict";
+
+function _getPath() {
+  if (window.location.protocol == "chrome:") {
+    return "/chrome/dom/browser-element/mochitest";
+  }
+  return window.location.pathname
+    .substring(0, window.location.pathname.lastIndexOf("/"))
+    .replace("/priority", "");
+}
+
+const browserElementTestHelpers = {
+  _getBoolPref(pref) {
+    try {
+      return SpecialPowers.getBoolPref(pref);
+    } catch (e) {
+      return undefined;
+    }
+  },
+
+  _setPref(pref, value) {
+    this.lockTestReady();
+    if (value !== undefined && value !== null) {
+      SpecialPowers.pushPrefEnv(
+        { set: [[pref, value]] },
+        this.unlockTestReady.bind(this)
+      );
+    } else {
+      SpecialPowers.pushPrefEnv(
+        { clear: [[pref]] },
+        this.unlockTestReady.bind(this)
+      );
+    }
+  },
+
+  _setPrefs() {
+    this.lockTestReady();
+    SpecialPowers.pushPrefEnv(
+      { set: Array.from(arguments) },
+      this.unlockTestReady.bind(this)
+    );
+  },
+
+  _testReadyLockCount: 0,
+  _firedTestReady: false,
+  lockTestReady() {
+    this._testReadyLockCount++;
+  },
+
+  unlockTestReady() {
+    this._testReadyLockCount--;
+    if (this._testReadyLockCount == 0 && !this._firedTestReady) {
+      this._firedTestReady = true;
+      dispatchEvent(new Event("testready"));
+    }
+  },
+
+  enableProcessPriorityManager() {
+    this._setPrefs(
+      ["dom.ipc.processPriorityManager.testMode", true],
+      ["dom.ipc.processPriorityManager.enabled", true]
+    );
+  },
+
+  setClipboardPlainTextOnlyPref(value) {
+    this._setPref("clipboard.plainTextOnly", value);
+  },
+
+  setEnabledPref(value) {
+    this._setPrefs(
+      ["dom.mozBrowserFramesEnabled", value],
+      ["network.disable.ipc.security", value]
+    );
+  },
+
+  setupAccessibleCaretPref() {
+    this._setPref("layout.accessiblecaret.enabled", true);
+    // Disable hide carets for mouse input for select-all tests so that we can
+    // get mozbrowsercaretstatechanged events.
+    this._setPref("layout.accessiblecaret.hide_carets_for_mouse_input", false);
+  },
+
+  getOOPByDefaultPref() {
+    return this._getBoolPref("dom.ipc.browser_frames.oop_by_default");
+  },
+
+  addPermission() {
+    this.lockTestReady();
+    SpecialPowers.pushPermissions(
+      [{ type: "browser", allow: 1, context: document }],
+      this.unlockTestReady.bind(this)
+    );
+  },
+
+  allowTopLevelDataURINavigation() {
+    this._setPref(
+      "security.data_uri.block_toplevel_data_uri_navigations",
+      false
+    );
+  },
+
+  _observers: [],
+
+  // This function is a wrapper which lets you register an observer to one of
+  // the process priority manager's test-only topics.  observerFn should be a
+  // function which takes (subject, topic, data).
+  //
+  // We'll clean up any observers you add at the end of the test.
+  addProcessPriorityObserver(processPriorityTopic, observerFn) {
+    var topic = "process-priority-manager:TEST-ONLY:" + processPriorityTopic;
+
+    // SpecialPowers appears to require that the observer be an object, not a
+    // function.
+    var observer = {
+      observe: observerFn,
+    };
+
+    SpecialPowers.addObserver(observer, topic);
+    this._observers.push([observer, topic]);
+  },
+
+  cleanUp() {
+    for (var i = 0; i < this._observers.length; i++) {
+      SpecialPowers.removeObserver(
+        this._observers[i][0],
+        this._observers[i][1]
+      );
+    }
+  },
+
+  // Some basically-empty pages from different domains you can load.
+  emptyPage1: "http://example.com" + _getPath() + "/file_empty.html",
+  fileEmptyPage1: "file_empty.html",
+  emptyPage2: "http://example.org" + _getPath() + "/file_empty.html",
+  emptyPage3: "http://test1.example.org" + _getPath() + "/file_empty.html",
+  focusPage: "http://example.org" + _getPath() + "/file_focus.html",
+};
+
+// Returns a promise which is resolved when a subprocess is created.  The
+// argument to resolve() is the childID of the subprocess.
+function expectProcessCreated(/* optional */ initialPriority) {
+  return new Promise(function(resolve, reject) {
+    var observed = false;
+    browserElementTestHelpers.addProcessPriorityObserver(
+      "process-created",
+      function(subject, topic, data) {
+        // Don't run this observer twice, so we don't ok(true) twice.  (It's fine
+        // to resolve a promise twice; the second resolve() call does nothing.)
+        if (observed) {
+          return;
+        }
+        observed = true;
+
+        var childID = parseInt(data);
+        ok(true, "Got new process, id=" + childID);
+        if (initialPriority) {
+          expectPriorityChange(childID, initialPriority).then(function() {
+            resolve(childID);
+          });
+        } else {
+          resolve(childID);
+        }
+      }
+    );
+  });
+}
+
+// Just like expectProcessCreated(), except we'll call ok(false) if a second
+// process is created.
+function expectOnlyOneProcessCreated(/* optional */ initialPriority) {
+  var p = expectProcessCreated(initialPriority);
+  p.then(function() {
+    expectProcessCreated().then(function(childID) {
+      ok(false, "Got unexpected process creation, childID=" + childID);
+    });
+  });
+  return p;
+}
+
+// Returns a promise which is resolved or rejected the next time the process
+// childID changes its priority. We resolve if the priority matches
+// expectedPriority, and we reject otherwise.
+
+function expectPriorityChange(childID, expectedPriority) {
+  return new Promise(function(resolve, reject) {
+    var observed = false;
+    browserElementTestHelpers.addProcessPriorityObserver(
+      "process-priority-set",
+      function(subject, topic, data) {
+        if (observed) {
+          return;
+        }
+
+        var [id, priority] = data.split(":");
+        if (id != childID) {
+          return;
+        }
+
+        // Make sure we run the is() calls in this observer only once, otherwise
+        // we'll expect /every/ priority change to match expectedPriority.
+        observed = true;
+
+        is(
+          priority,
+          expectedPriority,
+          "Expected priority of childID " +
+            childID +
+            " to change to " +
+            expectedPriority
+        );
+
+        if (priority == expectedPriority) {
+          resolve();
+        } else {
+          reject();
+        }
+      }
+    );
+  });
+}
+
+// Returns a promise which is resolved the first time the given iframe fires
+// the mozbrowser##eventName event.
+function expectMozbrowserEvent(iframe, eventName) {
+  return new Promise(function(resolve, reject) {
+    iframe.addEventListener("mozbrowser" + eventName, function handler(e) {
+      iframe.removeEventListener("mozbrowser" + eventName, handler);
+      resolve(e);
+    });
+  });
+}
+
+// Set some prefs:
+//
+//  * browser.pagethumbnails.capturing_disabled: true
+//
+//    Disable tab view; it seriously messes us up.
+//
+//  * dom.ipc.browser_frames.oop_by_default
+//
+//    Enable or disable OOP-by-default depending on the test's filename.  You
+//    can still force OOP on or off with <iframe mozbrowser remote=true/false>,
+//    at least until bug 756376 lands.
+//
+//  * dom.ipc.tabs.disabled: false
+//
+//    Allow us to create OOP frames.  Even if they're not the default, some
+//    "in-process" tests create OOP frames.
+//
+//  * network.disable.ipc.security: true
+//
+//    Disable the networking security checks; our test harness just tests
+//    browser elements without sticking them in apps, and the security checks
+//    dislike that.
+//
+//    Unfortunately setting network.disable.ipc.security to false before the
+//    child process(es) created by this test have shut down can cause us to
+//    assert and kill the child process.  That doesn't cause the tests to fail,
+//    but it's still scary looking.  So we just set the pref to true and never
+//    pop that value.  We'll rely on the tests which test IPC security to set
+//    it to false.
+//
+//  * security.mixed_content.block_active_content: false
+//
+//    Disable mixed active content blocking, so that tests can confirm that mixed
+//    content results in a broken security state.
+
+(function() {
+  var oop = !location.pathname.includes("_inproc_");
+
+  browserElementTestHelpers.lockTestReady();
+  SpecialPowers.setBoolPref("network.disable.ipc.security", true);
+  SpecialPowers.pushPrefEnv(
+    {
+      set: [
+        ["browser.pagethumbnails.capturing_disabled", true],
+        ["dom.ipc.browser_frames.oop_by_default", oop],
+        ["dom.ipc.tabs.disabled", false],
+        ["security.mixed_content.block_active_content", false],
+      ],
+    },
+    browserElementTestHelpers.unlockTestReady.bind(browserElementTestHelpers)
+  );
+})();
+
+addEventListener("unload", function() {
+  browserElementTestHelpers.cleanUp();
+});
+
+// Wait for the load event before unlocking the test-ready event.
+browserElementTestHelpers.lockTestReady();
+addEventListener("load", function() {
+  SimpleTest.executeSoon(
+    browserElementTestHelpers.unlockTestReady.bind(browserElementTestHelpers)
+  );
+});
diff --git a/dom/browser-element/mochitest/browserElement_Alert.js b/dom/browser-element/mochitest/browserElement_Alert.js
new file mode 100644
index 000000000000..b022211e1ef2
--- /dev/null
+++ b/dom/browser-element/mochitest/browserElement_Alert.js
@@ -0,0 +1,326 @@
+/* Any copyright is dedicated to the public domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+// Test that alert works.
+"use strict";
+
+/* global browserElementTestHelpers */
+
+SimpleTest.waitForExplicitFinish();
+browserElementTestHelpers.setEnabledPref(true);
+browserElementTestHelpers.addPermission();
+
+var numPendingChildTests = 0;
+var iframe;
+var mm;
+
+function runTest() {
+  iframe = document.createElement("iframe");
+  iframe.setAttribute("mozbrowser", "true");
+  document.body.appendChild(iframe);
+
+  mm = SpecialPowers.getBrowserFrameMessageManager(iframe);
+  mm.addMessageListener("test-success", function(msg) {
+    numPendingChildTests--;
+    ok(true, SpecialPowers.wrap(msg).json);
+  });
+  mm.addMessageListener("test-fail", function(msg) {
+    numPendingChildTests--;
+    ok(false, SpecialPowers.wrap(msg).json);
+  });
+
+  // Wait for the initial load to finish, then navigate the page, then wait
+  // for that load to finish, then start test1.
+  iframe.addEventListener(
+    "mozbrowserloadend",
+    function() {
+      iframe.src = browserElementTestHelpers.emptyPage1;
+
+      iframe.addEventListener(
+        "mozbrowserloadend",
+        function() {
+          SimpleTest.executeSoon(test1);
+        },
+        { once: true }
+      );
+    },
+    { once: true }
+  );
+}
+
+function test1() {
+  iframe.addEventListener("mozbrowsershowmodalprompt", test2);
+
+  // Do window.alert within the iframe, then modify the global |testState|
+  // after the alert.
+  var script =
+    'data:,\
+    this.testState = 0; \
+    content.alert("Hello, world!"); \
+    this.testState = 1; \
+  ';
+
+  mm.loadFrameScript(script, /* allowDelayedLoad = */ false);
+
+  // Triggers a mozbrowsershowmodalprompt event, which sends us down to test2.
+}
+
+// test2 is a mozbrowsershowmodalprompt listener.
+function test2(e) {
+  iframe.removeEventListener("mozbrowsershowmodalprompt", test2);
+
+  is(e.detail.message, "Hello, world!");
+  e.preventDefault(); // cause the alert to block.
+
+  SimpleTest.executeSoon(function() {
+    test2a(e);
+  });
+}
+
+function test2a(e) {
+  // The iframe should be blocked on the alert call at the moment, so testState
+  // should still be 0.
+  var script =
+    'data:,\
+    if (this.testState === 0) { \
+      sendAsyncMessage("test-success", "1: Correct testState"); \
+    } \
+    else { \
+      sendAsyncMessage("test-fail", "1: Wrong testState: " + this.testState); \
+    }';
+
+  mm.loadFrameScript(script, /* allowDelayedLoad = */ false);
+  numPendingChildTests++;
+
+  waitForPendingTests(function() {
+    test3(e);
+  });
+}
+
+function test3(e) {
+  // Now unblock the iframe and check that the script completed.
+  e.detail.unblock();
+
+  var script2 =
+    'data:,\
+    if (this.testState === 1) { \
+      sendAsyncMessage("test-success", "2: Correct testState"); \
+    } \
+    else { \
+      sendAsyncMessage("test-try-again", "2: Wrong testState (for now): " + this.testState); \
+    }';
+
+  // Urgh.  e.unblock() didn't necessarily unblock us immediately, so we have
+  // to spin and wait.
+  function onTryAgain() {
+    SimpleTest.executeSoon(function() {
+      // dump('onTryAgain\n');
+      mm.loadFrameScript(script2, /* allowDelayedLoad = */ false);
+    });
+  }
+
+  mm.addMessageListener("test-try-again", onTryAgain);
+  numPendingChildTests++;
+
+  onTryAgain();
+  waitForPendingTests(function() {
+    mm.removeMessageListener("test-try-again", onTryAgain);
+    test4();
+  });
+}
+
+function test4() {
+  // Navigate the iframe while an alert is pending.  This shouldn't screw
+  // things up.
+
+  iframe.addEventListener("mozbrowsershowmodalprompt", test5);
+
+  var script = 'data:,content.alert("test4");';
+  mm.loadFrameScript(script, /* allowDelayedLoad = */ false);
+}
+
+// test4 is a mozbrowsershowmodalprompt listener.
+function test5(e) {
+  iframe.removeEventListener("mozbrowsershowmodalprompt", test5);
+
+  is(e.detail.message, "test4");
+  e.preventDefault(); // cause the page to block.
+
+  SimpleTest.executeSoon(test5a);
+}
+
+function test5a() {
+  iframe.addEventListener("mozbrowserloadend", test5b);
+  iframe.src = browserElementTestHelpers.emptyPage2;
+}
+
+function test5b() {
+  iframe.removeEventListener("mozbrowserloadend", test5b);
+  SimpleTest.executeSoon(test6);
+}
+
+// Test nested alerts
+var promptBlockers = [];
+function test6() {
+  iframe.addEventListener("mozbrowsershowmodalprompt", test6a);
+
+  var script =
+    "data:,\
+    this.testState = 0; \
+    content.alert(1); \
+    this.testState = 3; \
+  ";
+  mm.loadFrameScript(script, /* allowDelayedLoad = */ false);
+}
+
+function test6a(e) {
+  iframe.removeEventListener("mozbrowsershowmodalprompt", test6a);
+
+  is(e.detail.message, "1");
+  e.preventDefault(); // cause the alert to block.
+  promptBlockers.push(e);
+
+  SimpleTest.executeSoon(test6b);
+}
+
+function test6b() {
+  var script =
+    'data:,\
+    if (this.testState === 0) { \
+      sendAsyncMessage("test-success", "1: Correct testState"); \
+    } \
+    else { \
+      sendAsyncMessage("test-fail", "1: Wrong testState: " + this.testState); \
+    }';
+  mm.loadFrameScript(script, /* allowDelayedLoad = */ false);
+  numPendingChildTests++;
+
+  waitForPendingTests(test6c);
+}
+
+function test6c() {
+  iframe.addEventListener("mozbrowsershowmodalprompt", test6d);
+
+  var script =
+    "data:,\
+    this.testState = 1; \
+    content.alert(2); \
+    this.testState = 2; \
+  ";
+  mm.loadFrameScript(script, /* allowDelayedLoad = */ false);
+}
+
+function test6d(e) {
+  iframe.removeEventListener("mozbrowsershowmodalprompt", test6d);
+
+  is(e.detail.message, "2");
+  e.preventDefault(); // cause the alert to block.
+  promptBlockers.push(e);
+
+  SimpleTest.executeSoon(test6e);
+}
+
+function test6e() {
+  var script =
+    'data:,\
+    if (this.testState === 1) { \
+      sendAsyncMessage("test-success", "2: Correct testState"); \
+    } \
+    else { \
+      sendAsyncMessage("test-fail", "2: Wrong testState: " + this.testState); \
+    }';
+  mm.loadFrameScript(script, /* allowDelayedLoad = */ false);
+  numPendingChildTests++;
+
+  waitForPendingTests(test6f);
+}
+
+function test6f() {
+  var e = promptBlockers.pop();
+  // Now unblock the iframe and check that the script completed.
+  e.detail.unblock();
+
+  var script2 =
+    'data:,\
+    if (this.testState === 2) { \
+      sendAsyncMessage("test-success", "3: Correct testState"); \
+    } \
+    else { \
+      sendAsyncMessage("test-try-again", "3: Wrong testState (for now): " + this.testState); \
+    }';
+
+  // Urgh.  e.unblock() didn't necessarily unblock us immediately, so we have
+  // to spin and wait.
+  function onTryAgain() {
+    SimpleTest.executeSoon(function() {
+      // dump('onTryAgain\n');
+      mm.loadFrameScript(script2, /* allowDelayedLoad = */ false);
+    });
+  }
+
+  mm.addMessageListener("test-try-again", onTryAgain);
+  numPendingChildTests++;
+
+  onTryAgain();
+  waitForPendingTests(function() {
+    mm.removeMessageListener("test-try-again", onTryAgain);
+    test6g();
+  });
+}
+
+function test6g() {
+  var e = promptBlockers.pop();
+  // Now unblock the iframe and check that the script completed.
+  e.detail.unblock();
+
+  var script2 =
+    'data:,\
+    if (this.testState === 3) { \
+      sendAsyncMessage("test-success", "4: Correct testState"); \
+    } \
+    else { \
+      sendAsyncMessage("test-try-again", "4: Wrong testState (for now): " + this.testState); \
+    }';
+
+  // Urgh.  e.unblock() didn't necessarily unblock us immediately, so we have
+  // to spin and wait.
+  function onTryAgain() {
+    SimpleTest.executeSoon(function() {
+      // dump('onTryAgain\n');
+      mm.loadFrameScript(script2, /* allowDelayedLoad = */ false);
+    });
+  }
+
+  mm.addMessageListener("test-try-again", onTryAgain);
+  numPendingChildTests++;
+
+  onTryAgain();
+  waitForPendingTests(function() {
+    mm.removeMessageListener("test-try-again", onTryAgain);
+    test6h();
+  });
+}
+
+function test6h() {
+  SimpleTest.finish();
+}
+
+var prevNumPendingTests = null;
+function waitForPendingTests(next) {
+  if (numPendingChildTests !== prevNumPendingTests) {
+    dump("Waiting for end; " + numPendingChildTests + " pending tests\n");
+    prevNumPendingTests = numPendingChildTests;
+  }
+
+  if (numPendingChildTests > 0) {
+    SimpleTest.executeSoon(function() {
+      waitForPendingTests(next);
+    });
+    return;
+  }
+
+  prevNumPendingTests = null;
+  next();
+}
+
+addEventListener("testready", runTest);
diff --git a/dom/browser-element/mochitest/browserElement_AlertInFrame.js b/dom/browser-element/mochitest/browserElement_AlertInFrame.js
new file mode 100644
index 000000000000..77a9537a4167
--- /dev/null
+++ b/dom/browser-element/mochitest/browserElement_AlertInFrame.js
@@ -0,0 +1,26 @@
+/* Any copyright is dedicated to the public domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+// Test that alert works from inside an <iframe> inside an <iframe mozbrowser>.
+"use strict";
+
+/* global browserElementTestHelpers */
+
+SimpleTest.waitForExplicitFinish();
+browserElementTestHelpers.setEnabledPref(true);
+browserElementTestHelpers.addPermission();
+
+function runTest() {
+  var iframe = document.createElement("iframe");
+  iframe.setAttribute("mozbrowser", "true");
+
+  iframe.addEventListener("mozbrowsershowmodalprompt", function(e) {
+    is(e.detail.message, "Hello");
+    SimpleTest.finish();
+  });
+
+  iframe.src = "file_browserElement_AlertInFrame.html";
+  document.body.appendChild(iframe);
+}
+
+addEventListener("testready", runTest);
diff --git a/dom/browser-element/mochitest/browserElement_Auth.js b/dom/browser-element/mochitest/browserElement_Auth.js
new file mode 100644
index 000000000000..446b9d4af69a
--- /dev/null
+++ b/dom/browser-element/mochitest/browserElement_Auth.js
@@ -0,0 +1,378 @@
+/* Any copyright is dedicated to the public domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+// Test that auth prompt works.
+"use strict";
+
+/* global browserElementTestHelpers */
+
+SimpleTest.waitForExplicitFinish();
+browserElementTestHelpers.setEnabledPref(true);
+browserElementTestHelpers.addPermission();
+
+const { NetUtil } = SpecialPowers.Cu.import(
+  "resource://gre/modules/NetUtil.jsm"
+);
+
+function testFail(msg) {
+  ok(false, JSON.stringify(msg));
+}
+
+var iframe;
+
+function runTest() {
+  iframe = document.createElement("iframe");
+  iframe.setAttribute("mozbrowser", "true");
+  document.body.appendChild(iframe);
+
+  // Wait for the initial load to finish, then navigate the page, then start test
+  // by loading SJS with http 401 response.
+  iframe.addEventListener(
+    "mozbrowserloadend",
+    function() {
+      iframe.addEventListener(
+        "mozbrowserusernameandpasswordrequired",
+        testHttpAuthCancel
+      );
+      SimpleTest.executeSoon(function() {
+        // Use absolute path because we need to specify host.
+        iframe.src =
+          "http://test/tests/dom/browser-element/mochitest/file_http_401_response.sjs";
+      });
+    },
+    { once: true }
+  );
+}
+
+function testHttpAuthCancel(e) {
+  iframe.removeEventListener(
+    "mozbrowserusernameandpasswordrequired",
+    testHttpAuthCancel
+  );
+  // Will cancel authentication, but prompt should not be shown again. Instead,
+  // we will be led to fail message
+  iframe.addEventListener("mozbrowserusernameandpasswordrequired", testFail);
+  iframe.addEventListener(
+    "mozbrowsertitlechange",
+    function(f) {
+      iframe.removeEventListener(
+        "mozbrowserusernameandpasswordrequired",
+        testFail
+      );
+      is(f.detail, "http auth failed", "expected authentication to fail");
+      iframe.addEventListener(
+        "mozbrowserusernameandpasswordrequired",
+        testHttpAuth
+      );
+      SimpleTest.executeSoon(function() {
+        // Use absolute path because we need to specify host.
+        iframe.src =
+          "http://test/tests/dom/browser-element/mochitest/file_http_401_response.sjs";
+      });
+    },
+    { once: true }
+  );
+
+  is(e.detail.realm, "http_realm", "expected realm matches");
+  is(e.detail.host, "http://test", "expected host matches");
+  is(
+    e.detail.path,
+    "/tests/dom/browser-element/mochitest/file_http_401_response.sjs",
+    "expected path matches"
+  );
+  e.preventDefault();
+
+  SimpleTest.executeSoon(function() {
+    e.detail.cancel();
+  });
+}
+
+function testHttpAuth(e) {
+  iframe.removeEventListener(
+    "mozbrowserusernameandpasswordrequired",
+    testHttpAuth
+  );
+
+  // Will authenticate with correct password, prompt should not be
+  // called again.
+  iframe.addEventListener("mozbrowserusernameandpasswordrequired", testFail);
+  iframe.addEventListener(
+    "mozbrowsertitlechange",
+    function(f) {
+      iframe.removeEventListener(
+        "mozbrowserusernameandpasswordrequired",
+        testFail
+      );
+      is(f.detail, "http auth success", "expect authentication to succeed");
+      SimpleTest.executeSoon(testProxyAuth);
+    },
+    { once: true }
+  );
+
+  is(e.detail.realm, "http_realm", "expected realm matches");
+  is(e.detail.host, "http://test", "expected host matches");
+  is(
+    e.detail.path,
+    "/tests/dom/browser-element/mochitest/file_http_401_response.sjs",
+    "expected path matches"
+  );
+  is(e.detail.isProxy, false, "expected isProxy is false");
+  e.preventDefault();
+
+  SimpleTest.executeSoon(function() {
+    e.detail.authenticate("httpuser", "httppass");
+  });
+}
+
+function testProxyAuth() {
+  // The testingSJS simulates the 407 proxy authentication required response
+  // for proxy server, which will trigger the browser element to send prompt
+  // event with proxy infomation.
+  var testingSJS =
+    "http://test/tests/dom/browser-element/mochitest/file_http_407_response.sjs";
+  var mozproxy;
+
+  function onUserNameAndPasswordRequired(e) {
+    iframe.removeEventListener(
+      "mozbrowserusernameandpasswordrequired",
+      onUserNameAndPasswordRequired
+    );
+    iframe.addEventListener(
+      "mozbrowsertitlechange",
+      function(event) {
+        iframe.removeEventListener(
+          "mozbrowserusernameandpasswordrequired",
+          testFail
+        );
+        is(
+          event.detail,
+          "http auth success",
+          "expect authentication to succeed"
+        );
+        SimpleTest.executeSoon(testAuthJarNoInterfere);
+      },
+      { once: true }
+    );
+
+    is(e.detail.realm, "http_realm", "expected realm matches");
+    is(e.detail.host, mozproxy, "expected host matches");
+    is(
+      e.detail.path,
+      "/tests/dom/browser-element/mochitest/file_http_407_response.sjs",
+      "expected path matches"
+    );
+    is(e.detail.isProxy, true, "expected isProxy is true");
+    e.preventDefault();
+
+    SimpleTest.executeSoon(function() {
+      e.detail.authenticate("proxyuser", "proxypass");
+    });
+  }
+
+  // Resolve proxy information used by the test suite, we need it to validate
+  // whether the proxy information delivered with the prompt event is correct.
+  var resolveCallback = SpecialPowers.wrapCallbackObject({
+    // eslint-disable-next-line mozilla/use-chromeutils-generateqi
+    QueryInterface(iid) {
+      const interfaces = [Ci.nsIProtocolProxyCallback, Ci.nsISupports];
+      if (
+        !interfaces.some(function(v) {
+          return iid.equals(v);
+        })
+      ) {
+        throw SpecialPowers.Cr.NS_ERROR_NO_INTERFACE;
+      }
+      return this;
+    },
+
+    onProxyAvailable(req, channel, pi, status) {
+      isnot(pi, null, "expected proxy information available");
+      if (pi) {
+        mozproxy = "moz-proxy://" + pi.host + ":" + pi.port;
+      }
+      iframe.addEventListener(
+        "mozbrowserusernameandpasswordrequired",
+        onUserNameAndPasswordRequired
+      );
+
+      iframe.src = testingSJS;
+    },
+  });
+
+  var channel = NetUtil.newChannel({
+    uri: testingSJS,
+    loadUsingSystemPrincipal: true,
+  });
+
+  var pps = SpecialPowers.Cc[
+    "@mozilla.org/network/protocol-proxy-service;1"
+  ].getService();
+
+  pps.asyncResolve(channel, 0, resolveCallback);
+}
+
+function testAuthJarNoInterfere(e) {
+  let authMgr = SpecialPowers.Cc[
+    "@mozilla.org/network/http-auth-manager;1"
+  ].getService(SpecialPowers.Ci.nsIHttpAuthManager);
+  let secMan = SpecialPowers.Services.scriptSecurityManager;
+  let ioService = SpecialPowers.Services.io;
+  var uri = ioService.newURI(
+    "http://test/tests/dom/browser-element/mochitest/file_http_401_response.sjs"
+  );
+
+  // Set a bunch of auth data that should not conflict with the correct auth data already
+  // stored in the cache.
+  var attrs = { userContextId: 1 };
+  var principal = secMan.createContentPrincipal(uri, attrs);
+  authMgr.setAuthIdentity(
+    "http",
+    "test",
+    -1,
+    "basic",
+    "http_realm",
+    "tests/dom/browser-element/mochitest/file_http_401_response.sjs",
+    "",
+    "httpuser",
+    "wrongpass",
+    false,
+    principal
+  );
+  attrs = { userContextId: 1, inIsolatedMozBrowser: true };
+  principal = secMan.createContentPrincipal(uri, attrs);
+  authMgr.setAuthIdentity(
+    "http",
+    "test",
+    -1,
+    "basic",
+    "http_realm",
+    "tests/dom/browser-element/mochitest/file_http_401_response.sjs",
+    "",
+    "httpuser",
+    "wrongpass",
+    false,
+    principal
+  );
+  principal = secMan.createContentPrincipal(uri, {});
+  authMgr.setAuthIdentity(
+    "http",
+    "test",
+    -1,
+    "basic",
+    "http_realm",
+    "tests/dom/browser-element/mochitest/file_http_401_response.sjs",
+    "",
+    "httpuser",
+    "wrongpass",
+    false,
+    principal
+  );
+
+  // Will authenticate with correct password, prompt should not be
+  // called again.
+  iframe.addEventListener("mozbrowserusernameandpasswordrequired", testFail);
+  iframe.addEventListener(
+    "mozbrowsertitlechange",
+    function(f) {
+      iframe.removeEventListener(
+        "mozbrowserusernameandpasswordrequired",
+        testFail
+      );
+      is(f.detail, "http auth success", "expected authentication success");
+      SimpleTest.executeSoon(testAuthJarInterfere);
+    },
+    { once: true }
+  );
+
+  // Once more with feeling. Ensure that our new auth data doesn't interfere with this mozbrowser's
+  // auth data.
+  iframe.src =
+    "http://test/tests/dom/browser-element/mochitest/file_http_401_response.sjs";
+}
+
+function testAuthJarInterfere(e) {
+  let authMgr = SpecialPowers.Cc[
+    "@mozilla.org/network/http-auth-manager;1"
+  ].getService(SpecialPowers.Ci.nsIHttpAuthManager);
+  let secMan = SpecialPowers.Services.scriptSecurityManager;
+  let ioService = SpecialPowers.Services.io;
+  var uri = ioService.newURI(
+    "http://test/tests/dom/browser-element/mochitest/file_http_401_response.sjs"
+  );
+
+  // Set some auth data that should overwrite the successful stored details.
+  var principal = secMan.createContentPrincipal(uri, {
+    inIsolatedMozBrowser: true,
+  });
+  authMgr.setAuthIdentity(
+    "http",
+    "test",
+    -1,
+    "basic",
+    "http_realm",
+    "tests/dom/browser-element/mochitest/file_http_401_response.sjs",
+    "",
+    "httpuser",
+    "wrongpass",
+    false,
+    principal
+  );
+
+  // Will authenticate with correct password, prompt should not be
+  // called again.
+  var gotusernamepasswordrequired = false;
+  function onUserNameAndPasswordRequired() {
+    gotusernamepasswordrequired = true;
+  }
+  iframe.addEventListener(
+    "mozbrowserusernameandpasswordrequired",
+    onUserNameAndPasswordRequired
+  );
+  iframe.addEventListener(
+    "mozbrowsertitlechange",
+    function(f) {
+      iframe.removeEventListener(
+        "mozbrowserusernameandpasswordrequired",
+        onUserNameAndPasswordRequired
+      );
+      ok(
+        gotusernamepasswordrequired,
+        "Should have dispatched mozbrowserusernameandpasswordrequired event"
+      );
+      testFinish();
+    },
+    { once: true }
+  );
+
+  // Once more with feeling. Ensure that our new auth data interferes with this mozbrowser's
+  // auth data.
+  iframe.src =
+    "http://test/tests/dom/browser-element/mochitest/file_http_401_response.sjs";
+}
+
+function testFinish() {
+  // Clear login information stored in password manager.
+  let authMgr = SpecialPowers.Cc[
+    "@mozilla.org/network/http-auth-manager;1"
+  ].getService(SpecialPowers.Ci.nsIHttpAuthManager);
+  authMgr.clearAll();
+
+  SpecialPowers.Services.logins.removeAllLogins();
+
+  SimpleTest.finish();
+}
+
+addEventListener("testready", function() {
+  // Enable http authentiication.
+  SpecialPowers.pushPrefEnv(
+    {
+      set: [
+        [
+          "network.auth.non-web-content-triggered-resources-http-auth-allow",
+          true,
+        ],
+      ],
+    },
+    runTest
+  );
+});
diff --git a/dom/browser-element/mochitest/browserElement_BackForward.js b/dom/browser-element/mochitest/browserElement_BackForward.js
new file mode 100644
index 000000000000..79c04215826e
--- /dev/null
+++ b/dom/browser-element/mochitest/browserElement_BackForward.js
@@ -0,0 +1,115 @@
+/* Any copyright is dedicated to the public domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+// Bug 741755 - Test that canGo{Back,Forward} and go{Forward,Back} work with
+// <iframe mozbrowser>.
+
+"use strict";
+
+/* global browserElementTestHelpers */
+
+SimpleTest.waitForExplicitFinish();
+browserElementTestHelpers.setEnabledPref(true);
+
+var iframe;
+function addOneShotIframeEventListener(event, fn) {
+  function wrapper(e) {
+    iframe.removeEventListener(event, wrapper);
+    fn(e);
+  }
+
+  iframe.addEventListener(event, wrapper);
+}
+
+function runTest() {
+  iframe = document.createElement("iframe");
+  iframe.setAttribute("mozbrowser", "true");
+
+  addOneShotIframeEventListener("mozbrowserloadend", function() {
+    SimpleTest.executeSoon(test2);
+  });
+
+  iframe.src = browserElementTestHelpers.emptyPage1;
+  document.body.appendChild(iframe);
+}
+
+function checkCanGoBackAndForward(canGoBack, canGoForward, nextTest) {
+  var seenCanGoBackResult = false;
+  iframe.getCanGoBack().then(function(result) {
+    is(
+      seenCanGoBackResult,
+      false,
+      "onsuccess handler shouldn't be called twice."
+    );
+    seenCanGoBackResult = true;
+    is(result, canGoBack);
+    maybeRunNextTest();
+  });
+
+  var seenCanGoForwardResult = false;
+  iframe.getCanGoForward().then(function(result) {
+    is(
+      seenCanGoForwardResult,
+      false,
+      "onsuccess handler shouldn't be called twice."
+    );
+    seenCanGoForwardResult = true;
+    is(result, canGoForward);
+    maybeRunNextTest();
+  });
+
+  function maybeRunNextTest() {
+    if (seenCanGoBackResult && seenCanGoForwardResult) {
+      nextTest();
+    }
+  }
+}
+
+function test2() {
+  checkCanGoBackAndForward(false, false, test3);
+}
+
+function test3() {
+  addOneShotIframeEventListener("mozbrowserloadend", function() {
+    checkCanGoBackAndForward(true, false, test4);
+  });
+
+  SimpleTest.executeSoon(function() {
+    iframe.src = browserElementTestHelpers.emptyPage2;
+  });
+}
+
+function test4() {
+  addOneShotIframeEventListener("mozbrowserlocationchange", function(e) {
+    is(e.detail.url, browserElementTestHelpers.emptyPage3);
+    is(e.detail.canGoBack, true);
+    is(e.detail.canGoForward, false);
+    checkCanGoBackAndForward(true, false, test5);
+  });
+
+  SimpleTest.executeSoon(function() {
+    iframe.src = browserElementTestHelpers.emptyPage3;
+  });
+}
+
+function test5() {
+  addOneShotIframeEventListener("mozbrowserlocationchange", function(e) {
+    is(e.detail.url, browserElementTestHelpers.emptyPage2);
+    is(e.detail.canGoBack, true);
+    is(e.detail.canGoForward, true);
+    checkCanGoBackAndForward(true, true, test6);
+  });
+  iframe.goBack();
+}
+
+function test6() {
+  addOneShotIframeEventListener("mozbrowserlocationchange", function(e) {
+    is(e.detail.url, browserElementTestHelpers.emptyPage1);
+    is(e.detail.canGoBack, false);
+    is(e.detail.canGoForward, true);
+    checkCanGoBackAndForward(false, true, SimpleTest.finish);
+  });
+  iframe.goBack();
+}
+
+addEventListener("testready", runTest);
diff --git a/dom/browser-element/mochitest/browserElement_BrowserWindowResize.js b/dom/browser-element/mochitest/browserElement_BrowserWindowResize.js
new file mode 100644
index 000000000000..318bfd970b6c
--- /dev/null
+++ b/dom/browser-element/mochitest/browserElement_BrowserWindowResize.js
@@ -0,0 +1,56 @@
+/* Any copyright is dedicated to the public domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+// Bug 891763 - Test the mozbrowserresize event
+"use strict";
+
+/* global browserElementTestHelpers */
+
+SimpleTest.waitForExplicitFinish();
+browserElementTestHelpers.setEnabledPref(true);
+browserElementTestHelpers.addPermission();
+browserElementTestHelpers.allowTopLevelDataURINavigation();
+
+function runTest() {
+  var srcResizeTo =
+    "data:text/html,       \
+    <script type='application/javascript'> \
+      window.resizeTo(300, 300);           \
+    </script>                             \
+  ";
+
+  var srcResizeBy =
+    "data:text/html,       \
+    <script type='application/javascript'> \
+      window.resizeBy(-100, -100);         \
+    </script>                             \
+  ";
+
+  var count = 0;
+  function checkSize(iframe) {
+    count++;
+    is(iframe.clientWidth, 400, "iframe width does not change");
+    is(iframe.clientHeight, 400, "iframe height does not change");
+    if (count == 2) {
+      SimpleTest.finish();
+    }
+  }
+
+  function testIFrameWithSrc(src) {
+    var iframe = document.createElement("iframe");
+    iframe.setAttribute("mozbrowser", "true");
+    iframe.style = "border:none; width:400px; height:400px;";
+    iframe.src = src;
+    iframe.addEventListener("mozbrowserresize", function(e) {
+      is(e.detail.width, 300, "Received correct resize event width");
+      is(e.detail.height, 300, "Received correct resize event height");
+      SimpleTest.executeSoon(checkSize.bind(undefined, iframe));
+    });
+    document.body.appendChild(iframe);
+  }
+
+  testIFrameWithSrc(srcResizeTo);
+  testIFrameWithSrc(srcResizeBy);
+}
+
+addEventListener("testready", runTest);
diff --git a/dom/browser-element/mochitest/browserElement_Close.js b/dom/browser-element/mochitest/browserElement_Close.js
new file mode 100644
index 000000000000..d39aa364c3ba
--- /dev/null
+++ b/dom/browser-element/mochitest/browserElement_Close.js
@@ -0,0 +1,28 @@
+/* Any copyright is dedicated to the public domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+// Test that window.close() works.
+"use strict";
+
+/* global browserElementTestHelpers */
+
+SimpleTest.waitForExplicitFinish();
+browserElementTestHelpers.setEnabledPref(true);
+browserElementTestHelpers.addPermission();
+browserElementTestHelpers.allowTopLevelDataURINavigation();
+
+function runTest() {
+  var iframe = document.createElement("iframe");
+  iframe.setAttribute("mozbrowser", "true");
+  document.body.appendChild(iframe);
+
+  iframe.addEventListener("mozbrowserclose", function(e) {
+    ok(true, "got mozbrowserclose event.");
+    SimpleTest.finish();
+  });
+
+  iframe.src =
+    "data:text/html,<html><body><script>window.close()</script></body></html>";
+}
+
+addEventListener("testready", runTest);
diff --git a/dom/browser-element/mochitest/browserElement_ContextmenuEvents.js b/dom/browser-element/mochitest/browserElement_ContextmenuEvents.js
new file mode 100644
index 000000000000..ca4909a4fc7a
--- /dev/null
+++ b/dom/browser-element/mochitest/browserElement_ContextmenuEvents.js
@@ -0,0 +1,474 @@
+"use strict";
+
+/* global browserElementTestHelpers */
+/* eslint-env mozilla/frame-script */
+
+SimpleTest.waitForExplicitFinish();
+browserElementTestHelpers.setEnabledPref(true);
+browserElementTestHelpers.setClipboardPlainTextOnlyPref(false);
+browserElementTestHelpers.addPermission();
+browserElementTestHelpers.allowTopLevelDataURINavigation();
+
+var audioUrl =
+  "http://mochi.test:8888/tests/dom/browser-element/mochitest/audio.ogg";
+var videoUrl =
+  "http://mochi.test:8888/tests/dom/browser-element/mochitest/short-video.ogv";
+
+function runTests() {
+  createIframe(function onIframeLoaded() {
+    checkEmptyContextMenu();
+  });
+}
+
+function checkEmptyContextMenu() {
+  sendContextMenuTo("body", function onContextMenu(detail) {
+    is(detail.contextmenu, null, "Body context clicks have no context menu");
+
+    checkInnerContextMenu();
+  });
+}
+
+function checkInnerContextMenu() {
+  sendContextMenuTo("#inner-link", function onContextMenu(detail) {
+    is(detail.systemTargets.length, 1, "Includes anchor data");
+    is(
+      detail.contextmenu.items.length,
+      3,
+      "Inner clicks trigger correct customized menu"
+    );
+    is(
+      detail.contextmenu.items[0].label,
+      "foo",
+      'Customized menu has a "foo" menu item'
+    );
+    is(
+      detail.contextmenu.items[1].label,
+      "bar",
+      'Customized menu has a "bar" menu item'
+    );
+    is(
+      detail.contextmenu.items[2].id,
+      "copy-link",
+      "#inner-link has a copy-link menu item"
+    );
+    is(
+      detail.contextmenu.customized,
+      true,
+      "Make sure contextmenu has customized items"
+    );
+
+    var target = detail.systemTargets[0];
+    is(target.nodeName, "A", "Reports correct nodeName");
+    is(target.data.uri, "foo.html", "Reports correct uri");
+    is(target.data.text, "Menu 1", "Reports correct link text");
+
+    checkCustomContextMenu();
+  });
+}
+
+function checkCustomContextMenu() {
+  sendContextMenuTo("#menu1-trigger", function onContextMenu(detail) {
+    is(detail.contextmenu.items.length, 2, "trigger custom contextmenu");
+
+    checkNestedContextMenu();
+  });
+}
+
+function checkNestedContextMenu() {
+  sendContextMenuTo("#menu2-trigger", function onContextMenu(detail) {
+    var innerMenu = detail.contextmenu.items.filter(function(x) {
+      return x.type === "menu";
+    });
+    is(detail.systemTargets.length, 2, "Includes two systemTargets");
+    is(detail.systemTargets[0].nodeName, "IMG", 'Includes "IMG" node');
+    is(
+      detail.systemTargets[0].data.uri,
+      "example.png",
+      "Img data has the correct uri"
+    );
+    is(detail.systemTargets[1].nodeName, "A", 'Includes "A" node');
+    is(
+      detail.systemTargets[1].data.uri,
+      "bar.html",
+      "Anchor has the correct uri"
+    );
+    ok(innerMenu.length > 0, "Menu contains a nested menu");
+
+    is(detail.contextmenu.items.length, 4, "We have correct # of menu items");
+    is(
+      detail.contextmenu.customized,
+      true,
+      "Make sure contextmenu has customized items"
+    );
+    is(
+      detail.contextmenu.items[0].label,
+      "outer",
+      'Customized menu has an "outer" menu item'
+    );
+    is(
+      detail.contextmenu.items[1].label,
+      "submenu",
+      'Customized menu has an "submenu" menu item'
+    );
+    is(
+      detail.contextmenu.items[2].id,
+      "copy-link",
+      "Has a copy-link menu item"
+    );
+    is(
+      detail.contextmenu.items[3].id,
+      "copy-image",
+      "Has a copy-image menu item"
+    );
+    checkPreviousContextMenuHandler();
+  });
+}
+
+// Finished testing the data passed to the contextmenu handler,
+// now we start selecting contextmenu items
+function checkPreviousContextMenuHandler() {
+  // This is previously triggered contextmenu data, since we have
+  // fired subsequent contextmenus this should not be mistaken
+  // for a current menuitem
+  var detail = previousContextMenuDetail;
+  var previousId = detail.contextmenu.items[0].id;
+  checkContextMenuCallbackForId(detail, previousId, function onCallbackFired(
+    label
+  ) {
+    is(label, null, "Callback label should be empty since this handler is old");
+
+    checkCurrentContextMenuHandler();
+  });
+}
+
+function checkCurrentContextMenuHandler() {
+  // This triggers a current menuitem
+  var detail = currentContextMenuDetail;
+
+  var innerMenu = detail.contextmenu.items.filter(function(x) {
+    return x.type === "menu";
+  });
+
+  var currentId = innerMenu[0].items[1].id;
+  checkContextMenuCallbackForId(detail, currentId, function onCallbackFired(
+    label
+  ) {
+    is(label, "inner 2", "Callback label should be set correctly");
+
+    checkAgainCurrentContextMenuHandler();
+  });
+}
+
+function checkAgainCurrentContextMenuHandler() {
+  // Once an item it selected, subsequent selections are ignored
+  var detail = currentContextMenuDetail;
+
+  var innerMenu = detail.contextmenu.items.filter(function(x) {
+    return x.type === "menu";
+  });
+
+  var currentId = innerMenu[0].items[1].id;
+  checkContextMenuCallbackForId(detail, currentId, function onCallbackFired(
+    label
+  ) {
+    is(
+      label,
+      null,
+      "Callback label should be empty since this handler has already been used"
+    );
+
+    checkCallbackWithPreventDefault();
+  });
+}
+
+// Finished testing callbacks if the embedder calls preventDefault() on the
+// mozbrowsercontextmenu event, now we start checking for some cases where the embedder
+// does not want to call preventDefault() for some reasons.
+function checkCallbackWithPreventDefault() {
+  sendContextMenuTo("#menu1-trigger", function onContextMenu(detail) {
+    var id = detail.contextmenu.items[0].id;
+    checkContextMenuCallbackForId(detail, id, function onCallbackFired(label) {
+      is(label, "foo", "Callback label should be set correctly");
+
+      checkCallbackWithoutPreventDefault();
+    });
+  });
+}
+
+function checkCallbackWithoutPreventDefault() {
+  sendContextMenuTo(
+    "#menu1-trigger",
+    function onContextMenu(detail) {
+      var id = detail.contextmenu.items[0].id;
+      checkContextMenuCallbackForId(detail, id, function onCallbackFired(
+        label
+      ) {
+        is(label, null, "Callback label should be null");
+
+        checkImageContextMenu();
+      });
+    },
+    /* ignorePreventDefault */ true
+  );
+}
+
+function checkImageContextMenu() {
+  sendContextMenuTo(
+    "#menu3-trigger",
+    function onContextMenu(detail) {
+      var target = detail.systemTargets[0];
+      is(target.nodeName, "IMG", "Reports correct nodeName");
+      is(target.data.uri, "example.png", "Reports correct uri");
+      is(detail.contextmenu.items.length, 1, "Reports correct # of menu items");
+      is(
+        detail.contextmenu.items[0].id,
+        "copy-image",
+        "IMG has a copy-image menu item"
+      );
+      is(
+        detail.contextmenu.customized,
+        false,
+        "Make sure we do not have customized items"
+      );
+
+      checkVideoContextMenu();
+    },
+    /* ignorePreventDefault */ true
+  );
+}
+
+function checkVideoContextMenu() {
+  sendContextMenuTo(
+    "#menu4-trigger",
+    function onContextMenu(detail) {
+      var target = detail.systemTargets[0];
+      is(target.nodeName, "VIDEO", "Reports correct nodeName");
+      is(target.data.uri, videoUrl, "Reports uri correctly in data");
+      is(target.data.hasVideo, true, 'Video data in video tag does "hasVideo"');
+
+      checkAudioContextMenu();
+    },
+    /* ignorePreventDefault */ true
+  );
+}
+
+function checkAudioContextMenu() {
+  sendContextMenuTo(
+    "#menu6-trigger",
+    function onContextMenu(detail) {
+      var target = detail.systemTargets[0];
+      is(target.nodeName, "AUDIO", "Reports correct nodeName");
+      is(target.data.uri, audioUrl, "Reports uri correctly in data");
+
+      checkAudioinVideoContextMenu();
+    },
+    /* ignorePreventDefault */ true
+  );
+}
+
+function checkAudioinVideoContextMenu() {
+  sendSrcTo("#menu5-trigger", audioUrl, function onSrcSet() {
+    sendContextMenuTo(
+      "#menu5-trigger",
+      function onContextMenu(detail) {
+        var target = detail.systemTargets[0];
+        is(target.nodeName, "VIDEO", "Reports correct nodeName");
+        is(target.data.uri, audioUrl, "Reports uri correctly in data");
+        is(
+          target.data.hasVideo,
+          false,
+          'Audio data in video tag reports no "hasVideo"'
+        );
+
+        checkFormNoMethod();
+      },
+      /* ignorePreventDefault */ true
+    );
+  });
+}
+
+function checkFormNoMethod() {
+  sendContextMenuTo(
+    "#menu7-trigger",
+    function onContextMenu(detail) {
+      var target = detail.systemTargets[0];
+      is(target.nodeName, "INPUT", "Reports correct nodeName");
+      is(target.data.method, "get", "Reports correct method");
+      is(target.data.action, "no_method", "Reports correct action url");
+      is(target.data.name, "input1", "Reports correct input name");
+
+      checkFormGetMethod();
+    },
+    /* ignorePreventDefault */ true
+  );
+}
+
+function checkFormGetMethod() {
+  sendContextMenuTo(
+    "#menu8-trigger",
+    function onContextMenu(detail) {
+      var target = detail.systemTargets[0];
+      is(target.nodeName, "INPUT", "Reports correct nodeName");
+      is(target.data.method, "get", "Reports correct method");
+      is(
+        target.data.action,
+        "http://example.com/get_method",
+        "Reports correct action url"
+      );
+      is(target.data.name, "input2", "Reports correct input name");
+
+      checkFormPostMethod();
+    },
+    /* ignorePreventDefault */ true
+  );
+}
+
+function checkFormPostMethod() {
+  sendContextMenuTo(
+    "#menu9-trigger",
+    function onContextMenu(detail) {
+      var target = detail.systemTargets[0];
+      is(target.nodeName, "INPUT", "Reports correct nodeName");
+      is(target.data.method, "post", "Reports correct method");
+      is(target.data.action, "post_method", "Reports correct action url");
+      is(target.data.name, "input3", "Reports correct input name");
+
+      SimpleTest.finish();
+    },
+    /* ignorePreventDefault */ true
+  );
+}
+
+/* Helpers */
+var mm = null;
+var previousContextMenuDetail = null;
+var currentContextMenuDetail = null;
+
+function sendSrcTo(selector, src, callback) {
+  mm.sendAsyncMessage("setsrc", { selector, src });
+  mm.addMessageListener("test:srcset", function onSrcSet(msg) {
+    mm.removeMessageListener("test:srcset", onSrcSet);
+    callback();
+  });
+}
+
+function sendContextMenuTo(selector, callback, ignorePreventDefault) {
+  iframe.addEventListener("mozbrowsercontextmenu", function oncontextmenu(e) {
+    iframe.removeEventListener(e.type, oncontextmenu);
+
+    // The embedder should call preventDefault() on the event if it will handle
+    // it. Not calling preventDefault() means it won't handle the event and
+    // should not be able to deal with context menu callbacks.
+    if (ignorePreventDefault !== true) {
+      e.preventDefault();
+    }
+
+    // Keep a reference to previous/current contextmenu event details.
+    previousContextMenuDetail = currentContextMenuDetail;
+    currentContextMenuDetail = e.detail;
+
+    setTimeout(function() {
+      callback(e.detail);
+    });
+  });
+
+  mm.sendAsyncMessage("contextmenu", { selector });
+}
+
+function checkContextMenuCallbackForId(detail, id, callback) {
+  mm.addMessageListener("test:callbackfired", function onCallbackFired(msg) {
+    mm.removeMessageListener("test:callbackfired", onCallbackFired);
+
+    msg = SpecialPowers.wrap(msg);
+    setTimeout(function() {
+      callback(msg.data.label);
+    });
+  });
+
+  detail.contextMenuItemSelected(id);
+}
+
+var iframe = null;
+function createIframe(callback) {
+  iframe = document.createElement("iframe");
+  iframe.setAttribute("mozbrowser", "true");
+
+  iframe.src =
+    "data:text/html,<html>" +
+    "<body>" +
+    '<menu type="context" id="menu1" label="firstmenu">' +
+    '<menuitem label="foo" onclick="window.onContextMenuCallbackFired(event)"></menuitem>' +
+    '<menuitem label="bar" onclick="window.onContextMenuCallbackFired(event)"></menuitem>' +
+    "</menu>" +
+    '<menu type="context" id="menu2" label="secondmenu">' +
+    '<menuitem label="outer" onclick="window.onContextMenuCallbackFired(event)"></menuitem>' +
+    '<menu label="submenu">' +
+    '<menuitem label="inner 1"></menuitem>' +
+    '<menuitem label="inner 2" onclick="window.onContextMenuCallbackFired(event)"></menuitem>' +
+    "</menu>" +
+    "</menu>" +
+    '<div id="menu1-trigger" contextmenu="menu1"><a id="inner-link" href="foo.html">Menu 1</a></div>' +
+    '<a href="bar.html" contextmenu="menu2"><img id="menu2-trigger" src="example.png" /></a>' +
+    '<img id="menu3-trigger" src="example.png" />' +
+    '<video id="menu4-trigger" src="' +
+    videoUrl +
+    '"></video>' +
+    '<video id="menu5-trigger" preload="metadata"></video>' +
+    '<audio id="menu6-trigger" src="' +
+    audioUrl +
+    '"></audio>' +
+    '<form action="no_method"><input id="menu7-trigger" name="input1"></input></form>' +
+    '<form action="http://example.com/get_method" method="get"><input id="menu8-trigger" name="input2"></input></form>' +
+    '<form action="post_method" method="post"><input id="menu9-trigger" name="input3"></input></form>' +
+    "</body></html>";
+  document.body.appendChild(iframe);
+
+  // The following code will be included in the child
+  // =========================================================================
+  function iframeScript() {
+    addMessageListener("contextmenu", function onContextMenu(msg) {
+      var document = content.document;
+      var evt = document.createEvent("HTMLEvents");
+      evt.initEvent("contextmenu", true, true);
+      document.querySelector(msg.data.selector).dispatchEvent(evt);
+    });
+
+    addMessageListener("setsrc", function onContextMenu(msg) {
+      var wrappedTarget = content.document.querySelector(msg.data.selector);
+      var target = XPCNativeWrapper.unwrap(wrappedTarget);
+      target.addEventListener("loadedmetadata", function() {
+        sendAsyncMessage("test:srcset");
+      });
+      target.src = msg.data.src;
+    });
+
+    addMessageListener("browser-element-api:call", function onCallback(msg) {
+      if (msg.data.msg_name != "fire-ctx-callback") {
+        return;
+      }
+
+      /* Use setTimeout in order to react *after* the platform */
+      content.setTimeout(function() {
+        sendAsyncMessage("test:callbackfired", { label });
+        label = null;
+      });
+    });
+
+    var label = null;
+    XPCNativeWrapper.unwrap(content).onContextMenuCallbackFired = function(e) {
+      label = e.target.getAttribute("label");
+    };
+  }
+  // =========================================================================
+
+  iframe.addEventListener("mozbrowserloadend", function onload(e) {
+    iframe.removeEventListener(e.type, onload);
+    mm = SpecialPowers.getBrowserFrameMessageManager(iframe);
+    mm.loadFrameScript("data:,(" + iframeScript.toString() + ")();", false);
+
+    // Now we're ready, let's start testing.
+    callback();
+  });
+}
+
+addEventListener("testready", runTests);
diff --git a/dom/browser-element/mochitest/browserElement_CookiesNotThirdParty.js b/dom/browser-element/mochitest/browserElement_CookiesNotThirdParty.js
new file mode 100644
index 000000000000..add7b393d3e7
--- /dev/null
+++ b/dom/browser-element/mochitest/browserElement_CookiesNotThirdParty.js
@@ -0,0 +1,57 @@
+/* Any copyright is dedicated to the public domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+// Bug 806127 - Test that cookies set by <iframe mozbrowser> are not considered
+// third-party.
+"use strict";
+
+/* global browserElementTestHelpers */
+
+SimpleTest.waitForExplicitFinish();
+browserElementTestHelpers.setEnabledPref(true);
+browserElementTestHelpers.addPermission();
+
+function runTest() {
+  const innerPage =
+    "http://example.com/tests/dom/browser-element/mochitest/file_browserElement_CookiesNotThirdParty.html";
+
+  var iframe = document.createElement("iframe");
+  iframe.setAttribute("mozbrowser", "true");
+
+  iframe.addEventListener("mozbrowsershowmodalprompt", function(e) {
+    if (e.detail.message == "next") {
+      iframe.src = innerPage + "?step=2";
+      return;
+    }
+
+    if (e.detail.message.startsWith("success:")) {
+      ok(true, e.detail.message);
+      return;
+    }
+
+    if (e.detail.message.startsWith("failure:")) {
+      ok(false, e.detail.message);
+      return;
+    }
+
+    if (e.detail.message == "finish") {
+      SimpleTest.finish();
+    }
+  });
+
+  // innerPage will set a cookie and then alert('next').  We'll load
+  // innerPage?step=2.  That page will check that the cooke exists (despite the
+  // fact that we've disabled third-party cookies) and alert('success:') or
+  // alert('failure:'), as appropriate.  Finally, the page will
+  // alert('finish');
+  iframe.src = innerPage;
+  document.body.appendChild(iframe);
+}
+
+// Disable third-party cookies for this test.
+addEventListener("testready", function() {
+  SpecialPowers.pushPrefEnv(
+    { set: [["network.cookie.cookieBehavior", 1]] },
+    runTest
+  );
+});
diff --git a/dom/browser-element/mochitest/browserElement_CopyPaste.js b/dom/browser-element/mochitest/browserElement_CopyPaste.js
new file mode 100644
index 000000000000..64beabf30716
--- /dev/null
+++ b/dom/browser-element/mochitest/browserElement_CopyPaste.js
@@ -0,0 +1,428 @@
+/* Any copyright is dedicated to the public domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+// Test that "cut, copy, paste, selectall" and caretstatechanged event works from inside an <iframe mozbrowser>.
+"use strict";
+
+/* global browserElementTestHelpers */
+
+SimpleTest.waitForExplicitFinish();
+SimpleTest.requestFlakyTimeout("untriaged");
+browserElementTestHelpers.setEnabledPref(true);
+browserElementTestHelpers.setupAccessibleCaretPref();
+browserElementTestHelpers.addPermission();
+browserElementTestHelpers.allowTopLevelDataURINavigation();
+
+var gTextarea = null;
+var mm;
+var iframeOuter;
+var iframeInner;
+var state = 0;
+var stateMeaning;
+var defaultData;
+var pasteData;
+var focusScript;
+var createEmbededFrame = false;
+var testSelectionChange = false;
+
+function copyToClipboard(str, callback) {
+  gTextarea.value = str;
+  SpecialPowers.wrap(gTextarea).editor.selectAll();
+  SimpleTest.waitForClipboard(
+    gTextarea.value,
+    () => {
+      SpecialPowers.wrap(gTextarea).editor.copy();
+    },
+    callback,
+    () => {
+      ok(false, "clipboard copy failed");
+    }
+  );
+}
+
+function getScriptForGetContent() {
+  var script =
+    'data:,\
+    var elt = content.document.getElementById("text"); \
+    var txt = ""; \
+    if (elt) { \
+      if (elt.tagName === "DIV" || elt.tagName === "BODY") { \
+        txt = elt.textContent; \
+      } else { \
+        txt = elt.value; \
+      } \
+    } \
+    sendAsyncMessage("content-text", txt);';
+  return script;
+}
+
+function getScriptForSetFocus() {
+  var script = "data:," + focusScript + 'sendAsyncMessage("content-focus")';
+  return script;
+}
+
+function runTest() {
+  iframeOuter = document.createElement("iframe");
+  iframeOuter.setAttribute("mozbrowser", "true");
+  if (createEmbededFrame) {
+    iframeOuter.src = "file_empty.html";
+  }
+  document.body.appendChild(iframeOuter);
+
+  gTextarea = document.createElement("textarea");
+  document.body.appendChild(gTextarea);
+
+  iframeOuter.addEventListener(
+    "mozbrowserloadend",
+    function(e) {
+      if (createEmbededFrame) {
+        var contentWin = SpecialPowers.wrap(iframeOuter).frameLoader.docShell
+          .contentViewer.DOMDocument.defaultView;
+        var contentDoc = contentWin.document;
+        iframeInner = contentDoc.createElement("iframe");
+        iframeInner.setAttribute("mozbrowser", true);
+        iframeInner.setAttribute("remote", "false");
+        contentDoc.body.appendChild(iframeInner);
+        iframeInner.addEventListener(
+          "mozbrowserloadend",
+          function(f) {
+            mm = SpecialPowers.getBrowserFrameMessageManager(iframeInner);
+            dispatchTest(f);
+          },
+          { once: true }
+        );
+      } else {
+        iframeInner = iframeOuter;
+        mm = SpecialPowers.getBrowserFrameMessageManager(iframeInner);
+        dispatchTest(e);
+      }
+    },
+    { once: true }
+  );
+}
+
+function doCommand(cmd) {
+  var COMMAND_MAP = {
+    cut: "cmd_cut",
+    copy: "cmd_copy",
+    paste: "cmd_paste",
+    selectall: "cmd_selectAll",
+  };
+  var script = 'data:,docShell.doCommand("' + COMMAND_MAP[cmd] + '");';
+  mm.loadFrameScript(script, false);
+}
+
+function dispatchTest(e) {
+  iframeInner.addEventListener(
+    "mozbrowserloadend",
+    function(f) {
+      iframeInner.focus();
+      SimpleTest.executeSoon(function() {
+        testSelectAll(f);
+      });
+    },
+    { once: true }
+  );
+
+  switch (state) {
+    case 0: // test for textarea
+      defaultData = "Test for selection change event";
+      pasteData = "from parent ";
+      iframeInner.src =
+        "data:text/html,<html><body>" +
+        "<textarea id='text'>" +
+        defaultData +
+        "</textarea>" +
+        "</body>" +
+        "</html>";
+      stateMeaning = " (test: textarea)";
+      focusScript =
+        "var elt=content.document.getElementById('text');elt.focus();elt.select();";
+      break;
+    case 1: // test for input text
+      defaultData = "Test for selection change event";
+      pasteData = "from parent ";
+      iframeInner.src =
+        "data:text/html,<html><body>" +
+        "<input type='text' id='text' value='" +
+        defaultData +
+        "'>" +
+        "</body>" +
+        "</html>";
+      stateMeaning = " (test: <input type=text>)";
+      focusScript =
+        "var elt=content.document.getElementById('text');elt.focus();elt.select();";
+      break;
+    case 2: // test for input number
+      defaultData = "12345";
+      pasteData = "67890";
+      iframeInner.src =
+        "data:text/html,<html><body>" +
+        "<input type='number' id='text' value='" +
+        defaultData +
+        "'>" +
+        "</body>" +
+        "</html>";
+      stateMeaning = " (test: <input type=number>)";
+      focusScript =
+        "var elt=content.document.getElementById('text');elt.focus();elt.select();";
+      break;
+    case 3: // test for div contenteditable
+      defaultData = "Test for selection change event";
+      pasteData = "from parent ";
+      iframeInner.src =
+        "data:text/html,<html><body>" +
+        "<div contenteditable='true' id='text'>" +
+        defaultData +
+        "</div>" +
+        "</body>" +
+        "</html>";
+      stateMeaning = " (test: content editable div)";
+      focusScript =
+        "var elt=content.document.getElementById('text');elt.focus();";
+      break;
+    case 4: // test for normal div
+      defaultData = "Test for selection change event";
+      pasteData = "from parent ";
+      iframeInner.src =
+        "data:text/html,<html><body>" +
+        "<div id='text'>" +
+        defaultData +
+        "</div>" +
+        "</body>" +
+        "</html>";
+      stateMeaning = " (test: normal div)";
+      focusScript =
+        "var elt=content.document.getElementById('text');elt.focus();";
+      break;
+    case 5: // test for normal div with designMode:on
+      defaultData = "Test for selection change event";
+      pasteData = "from parent ";
+      iframeInner.src =
+        "data:text/html,<html><body id='text'>" +
+        defaultData +
+        "</body>" +
+        "<script>document.designMode='on';</script>" +
+        "</html>";
+      stateMeaning = " (test: normal div with designMode:on)";
+      focusScript =
+        "var elt=content.document.getElementById('text');elt.focus();";
+      break;
+    default:
+      if (
+        createEmbededFrame ||
+        browserElementTestHelpers.getOOPByDefaultPref()
+      ) {
+        SimpleTest.finish();
+      } else {
+        createEmbededFrame = true;
+
+        // clean up and run test again.
+        document.body.removeChild(iframeOuter);
+        document.body.removeChild(gTextarea);
+        state = 0;
+        runTest();
+      }
+      break;
+  }
+}
+
+function isChildProcess() {
+  return (
+    SpecialPowers.Services.appinfo.processType !=
+    SpecialPowers.Ci.nsIXULRuntime.PROCESS_TYPE_DEFAULT
+  );
+}
+
+function testSelectAll(e) {
+  // Skip mozbrowser test if we're at child process.
+  if (!isChildProcess()) {
+    let eventName = "mozbrowsercaretstatechanged";
+    iframeOuter.addEventListener(
+      eventName,
+      function(f) {
+        ok(true, "got mozbrowsercaretstatechanged event." + stateMeaning);
+        ok(f.detail, "event.detail is not null." + stateMeaning);
+        ok(
+          f.detail.width != 0,
+          "event.detail.width is not zero" + stateMeaning
+        );
+        ok(
+          f.detail.height != 0,
+          "event.detail.height is not zero" + stateMeaning
+        );
+        SimpleTest.executeSoon(function() {
+          testCopy1(f);
+        });
+      },
+      { capture: true, once: true }
+    );
+  }
+
+  mm.addMessageListener("content-focus", function messageforfocus(msg) {
+    mm.removeMessageListener("content-focus", messageforfocus);
+    // test selectall command, after calling this the caretstatechanged event should be fired.
+    doCommand("selectall");
+    if (isChildProcess()) {
+      SimpleTest.executeSoon(function() {
+        testCopy1(e);
+      });
+    }
+  });
+
+  mm.loadFrameScript(getScriptForSetFocus(), false);
+}
+
+function testCopy1(e) {
+  // Right now we're at "selectall" state, so we can test copy commnad by
+  // calling doCommand
+  copyToClipboard("", () => {
+    let setup = function() {
+      doCommand("copy");
+    };
+
+    let nextTest = function(success) {
+      ok(success, "copy command works" + stateMeaning);
+      SimpleTest.executeSoon(function() {
+        testPaste1(e);
+      });
+    };
+
+    let success = function() {
+      nextTest(true);
+    };
+
+    let fail = function() {
+      nextTest(false);
+    };
+
+    let compareData = defaultData;
+    SimpleTest.waitForClipboard(compareData, setup, success, fail);
+  });
+}
+
+function testPaste1(e) {
+  // Next test paste command, first we copy to global clipboard in parent side.
+  // Then paste it to child side.
+  copyToClipboard(pasteData, () => {
+    doCommand("selectall");
+    doCommand("paste");
+    SimpleTest.executeSoon(function() {
+      testPaste2(e);
+    });
+  });
+}
+
+function testPaste2(e) {
+  mm.addMessageListener("content-text", function messageforpaste(msg) {
+    mm.removeMessageListener("content-text", messageforpaste);
+    if (state == 4) {
+      // normal div cannot paste, so the content remain unchange
+      ok(
+        SpecialPowers.wrap(msg).json === defaultData,
+        "paste command works" + stateMeaning
+      );
+    } else if (state == 3 && browserElementTestHelpers.getOOPByDefaultPref()) {
+      // Something weird when we doCommand with content editable element in OOP. Mark this case as todo
+      todo(false, "paste command works" + stateMeaning);
+    } else {
+      ok(
+        SpecialPowers.wrap(msg).json === pasteData,
+        "paste command works" + stateMeaning
+      );
+    }
+    SimpleTest.executeSoon(function() {
+      testCut1(e);
+    });
+  });
+
+  mm.loadFrameScript(getScriptForGetContent(), false);
+}
+
+function testCut1(e) {
+  // Clean clipboard first
+  copyToClipboard("", () => {
+    let setup = function() {
+      doCommand("selectall");
+      doCommand("cut");
+    };
+
+    let nextTest = function(success) {
+      if (state == 3 && browserElementTestHelpers.getOOPByDefaultPref()) {
+        // Something weird when we doCommand with content editable element in OOP.
+        todo(false, "cut function works" + stateMeaning);
+      } else {
+        ok(success, "cut function works" + stateMeaning);
+      }
+      SimpleTest.executeSoon(function() {
+        testCut2(e);
+      });
+    };
+
+    let success = function() {
+      nextTest(true);
+    };
+
+    let fail = function() {
+      nextTest(false);
+    };
+
+    let compareData = pasteData;
+
+    // Something weird when we doCommand with content editable element in OOP.
+    // Always true in this case
+    // Normal div case cannot cut, always true as well.
+    if (
+      (state == 3 && browserElementTestHelpers.getOOPByDefaultPref()) ||
+      state == 4
+    ) {
+      compareData = function() {
+        return true;
+      };
+    }
+
+    SimpleTest.waitForClipboard(compareData, setup, success, fail);
+  });
+}
+
+function testCut2(e) {
+  mm.addMessageListener("content-text", function messageforcut(msg) {
+    mm.removeMessageListener("content-text", messageforcut);
+    // normal div cannot cut
+    if (state == 4) {
+      ok(
+        SpecialPowers.wrap(msg).json !== "",
+        "cut command works" + stateMeaning
+      );
+    } else if (state == 3 && browserElementTestHelpers.getOOPByDefaultPref()) {
+      // Something weird when we doCommand with content editable element in OOP. Mark this case as todo
+      todo(false, "cut command works" + stateMeaning);
+    } else {
+      ok(
+        SpecialPowers.wrap(msg).json === "",
+        "cut command works" + stateMeaning
+      );
+    }
+
+    state++;
+    dispatchTest(e);
+  });
+
+  mm.loadFrameScript(getScriptForGetContent(), false);
+}
+
+// Give our origin permission to open browsers, and remove it when the test is complete.
+var principal = SpecialPowers.wrap(document).nodePrincipal;
+var context = {
+  url: SpecialPowers.wrap(principal.URI).spec,
+  originAttributes: {
+    inIsolatedMozBrowser: true,
+  },
+};
+
+addEventListener("testready", function() {
+  SpecialPowers.pushPermissions(
+    [{ type: "browser", allow: 1, context }],
+    runTest
+  );
+});
diff --git a/dom/browser-element/mochitest/browserElement_DataURI.js b/dom/browser-element/mochitest/browserElement_DataURI.js
new file mode 100644
index 000000000000..a053a7bcdb39
--- /dev/null
+++ b/dom/browser-element/mochitest/browserElement_DataURI.js
@@ -0,0 +1,74 @@
+/* Any copyright is dedicated to the public domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+// Test that data: URIs work with mozbrowserlocationchange events.
+
+"use strict";
+
+/* global browserElementTestHelpers */
+
+SimpleTest.waitForExplicitFinish();
+browserElementTestHelpers.setEnabledPref(true);
+browserElementTestHelpers.addPermission();
+browserElementTestHelpers.allowTopLevelDataURINavigation();
+
+function runTest() {
+  var iframe1 = document.createElement("iframe");
+  iframe1.setAttribute("mozbrowser", "true");
+  iframe1.id = "iframe1";
+  iframe1.addEventListener(
+    "mozbrowserloadend",
+    function() {
+      ok(true, "Got first loadend event.");
+      SimpleTest.executeSoon(runTest2);
+    },
+    { once: true }
+  );
+  iframe1.src = browserElementTestHelpers.emptyPage1;
+  document.body.appendChild(iframe1);
+
+  var iframe2 = document.createElement("iframe");
+  iframe2.id = "iframe2";
+  document.body.appendChild(iframe2);
+}
+
+function runTest2() {
+  var iframe1 = document.getElementById("iframe1");
+  var iframe2 = document.getElementById("iframe2");
+
+  var sawLoadEnd = false;
+  var sawLocationChange = false;
+
+  iframe1.addEventListener("mozbrowserlocationchange", function(e) {
+    ok(e.isTrusted, "Event should be trusted.");
+    ok(!sawLocationChange, "Just one locationchange event.");
+    ok(!sawLoadEnd, "locationchange before load.");
+    is(e.detail.url, "data:text/html,1", "event's reported location");
+    sawLocationChange = true;
+  });
+
+  iframe1.addEventListener("mozbrowserloadend", function() {
+    ok(sawLocationChange, "Loadend after locationchange.");
+    ok(!sawLoadEnd, "Just one loadend event.");
+    sawLoadEnd = true;
+  });
+
+  function iframe2Load() {
+    if (!sawLoadEnd || !sawLocationChange) {
+      // Spin if iframe1 hasn't loaded yet.
+      SimpleTest.executeSoon(iframe2Load);
+      return;
+    }
+    ok(true, "Got iframe2 load.");
+    SimpleTest.finish();
+  }
+  iframe2.addEventListener("load", iframe2Load);
+
+  iframe1.src = "data:text/html,1";
+
+  // Load something into iframe2 to check that it doesn't trigger a
+  // locationchange for our iframe1 listener.
+  iframe2.src = browserElementTestHelpers.emptyPage2;
+}
+
+addEventListener("testready", runTest);
diff --git a/dom/browser-element/mochitest/browserElement_DataURILoad.html b/dom/browser-element/mochitest/browserElement_DataURILoad.html
new file mode 100644
index 000000000000..3ea88a4e2501
--- /dev/null
+++ b/dom/browser-element/mochitest/browserElement_DataURILoad.html
@@ -0,0 +1,5 @@
+<html>
+<body>
+foo
+</body>
+</html>
diff --git a/dom/browser-element/mochitest/browserElement_DataURILoad.js b/dom/browser-element/mochitest/browserElement_DataURILoad.js
new file mode 100644
index 000000000000..af687ae74b2f
--- /dev/null
+++ b/dom/browser-element/mochitest/browserElement_DataURILoad.js
@@ -0,0 +1,72 @@
+/* Any copyright is dedicated to the public domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/* global browserElementTestHelpers */
+
+SimpleTest.waitForExplicitFinish();
+SimpleTest.requestFlakyTimeout(
+  "testing mozbrowser data: navigation is blocked"
+);
+
+browserElementTestHelpers.setEnabledPref(true);
+browserElementTestHelpers.addPermission();
+
+// make sure top level data: URI navigations are blocked.
+const PREF = "security.data_uri.block_toplevel_data_uri_navigations";
+browserElementTestHelpers._setPref(PREF, true);
+
+const INNER = "foo";
+const DATA_URI = "data:text/html,<html><body>" + INNER + "</body></html>";
+const HTTP_URI = "browserElement_DataURILoad.html";
+
+function runTest1() {
+  let frame = document.createElement("iframe");
+  frame.setAttribute("mozbrowser", "true");
+  frame.src = DATA_URI;
+  document.body.appendChild(frame);
+  let wrappedFrame = SpecialPowers.wrap(frame);
+
+  // wait for 1000ms and check that the data: URI did not load
+  setTimeout(function() {
+    isnot(
+      wrappedFrame.contentWindow.document.body.innerHTML,
+      INNER,
+      "data: URI navigation should be blocked"
+    );
+    runTest2();
+  }, 1000);
+}
+
+function runTest2() {
+  let frame = document.createElement("iframe");
+  frame.setAttribute("mozbrowser", "true");
+  frame.src = HTTP_URI;
+  document.body.appendChild(frame);
+  let wrappedFrame = SpecialPowers.wrap(frame);
+
+  wrappedFrame.addEventListener(
+    "mozbrowserloadend",
+    function onloadend(e) {
+      ok(
+        wrappedFrame.contentWindow.document.location.href.endsWith(HTTP_URI),
+        "http: URI navigation should be allowed"
+      );
+      frame.src = DATA_URI;
+
+      // wait for 1000ms and check that the data: URI did not load
+      setTimeout(function() {
+        isnot(
+          wrappedFrame.contentWindow.document.body.innerHTML,
+          INNER,
+          "data: URI navigation should be blocked"
+        );
+        SimpleTest.finish();
+      }, 1000);
+    },
+    { once: true }
+  );
+}
+
+addEventListener("testready", runTest1);
diff --git a/dom/browser-element/mochitest/browserElement_DocumentFirstPaint.js b/dom/browser-element/mochitest/browserElement_DocumentFirstPaint.js
new file mode 100644
index 000000000000..78672ea4644b
--- /dev/null
+++ b/dom/browser-element/mochitest/browserElement_DocumentFirstPaint.js
@@ -0,0 +1,77 @@
+/* Any copyright is dedicated to the public domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+// Bug 829486 - Add mozdocumentbrowserfirstpaint event.
+"use strict";
+
+/* global browserElementTestHelpers */
+
+SimpleTest.waitForExplicitFinish();
+browserElementTestHelpers.setEnabledPref(true);
+
+var iframe;
+
+function runTestQueue(queue) {
+  if (queue.length == 0) {
+    SimpleTest.finish();
+    return;
+  }
+
+  var gotFirstPaint = false;
+  var gotFirstLocationChange = false;
+  var test = queue.shift();
+
+  function runNext() {
+    iframe.removeEventListener(
+      "mozbrowserdocumentfirstpaint",
+      documentfirstpainthandler
+    );
+    iframe.removeEventListener("mozbrowserloadend", loadendhandler);
+    runTestQueue(queue);
+  }
+
+  function documentfirstpainthandler(e) {
+    ok(!gotFirstPaint, "Got firstpaint only once");
+    gotFirstPaint = true;
+    if (gotFirstLocationChange) {
+      runNext();
+    }
+  }
+
+  function loadendhandler(e) {
+    gotFirstLocationChange = true;
+    if (gotFirstPaint) {
+      runNext();
+    }
+  }
+
+  iframe.addEventListener(
+    "mozbrowserdocumentfirstpaint",
+    documentfirstpainthandler
+  );
+  iframe.addEventListener("mozbrowserloadend", loadendhandler);
+
+  test();
+}
+
+function testChangeLocation() {
+  iframe.src = browserElementTestHelpers.emptyPage1 + "?2";
+}
+
+function testReload() {
+  iframe.reload();
+}
+
+function testFirstLoad() {
+  document.body.appendChild(iframe);
+  iframe.src = browserElementTestHelpers.emptyPage1;
+}
+
+function runTest() {
+  iframe = document.createElement("iframe");
+  iframe.setAttribute("mozbrowser", "true");
+
+  runTestQueue([testFirstLoad, testReload, testChangeLocation]);
+}
+
+addEventListener("testready", runTest);
diff --git a/dom/browser-element/mochitest/browserElement_ErrorSecurity.js b/dom/browser-element/mochitest/browserElement_ErrorSecurity.js
new file mode 100644
index 000000000000..3569e817aa8e
--- /dev/null
+++ b/dom/browser-element/mochitest/browserElement_ErrorSecurity.js
@@ -0,0 +1,74 @@
+/* Any copyright is dedicated to the public domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+// Bug 764718 - Test that mozbrowsererror works for a security error.
+
+"use strict";
+
+/* global browserElementTestHelpers */
+
+SimpleTest.waitForExplicitFinish();
+browserElementTestHelpers.setEnabledPref(true);
+browserElementTestHelpers.addPermission();
+
+var iframe = null;
+function runTest() {
+  iframe = document.createElement("iframe");
+  iframe.setAttribute("mozbrowser", "true");
+  document.body.appendChild(iframe);
+
+  checkForDnsError();
+}
+
+function checkForDnsError() {
+  iframe.addEventListener("mozbrowsererror", function onDnsError(e) {
+    iframe.removeEventListener(e.type, onDnsError);
+    ok(true, "Got mozbrowsererror event.");
+    ok(
+      e.detail.type == "dnsNotFound",
+      "Event's detail has a |type| param with the value '" +
+        e.detail.type +
+        "'."
+    );
+
+    checkForExpiredCertificateError();
+  });
+
+  iframe.src = "http://this_is_not_a_domain.example.com";
+}
+
+function checkForExpiredCertificateError() {
+  iframe.addEventListener("mozbrowsererror", function onCertError(e) {
+    iframe.removeEventListener(e.type, onCertError);
+    ok(true, "Got mozbrowsererror event.");
+    ok(
+      e.detail.type == "certerror",
+      "Event's detail has a |type| param with the value '" +
+        e.detail.type +
+        "'."
+    );
+
+    checkForNoCertificateError();
+  });
+
+  iframe.src = "https://expired.example.com";
+}
+
+function checkForNoCertificateError() {
+  iframe.addEventListener("mozbrowsererror", function onCertError(e) {
+    iframe.removeEventListener(e.type, onCertError);
+    ok(true, "Got mozbrowsererror event.");
+    ok(
+      e.detail.type == "certerror",
+      "Event's detail has a |type| param with the value '" +
+        e.detail.type +
+        "'."
+    );
+
+    SimpleTest.finish();
+  });
+
+  iframe.src = "https://nocert.example.com";
+}
+
+addEventListener("testready", runTest);
diff --git a/dom/browser-element/mochitest/browserElement_ExposableURI.js b/dom/browser-element/mochitest/browserElement_ExposableURI.js
new file mode 100644
index 000000000000..f8118ddd3bce
--- /dev/null
+++ b/dom/browser-element/mochitest/browserElement_ExposableURI.js
@@ -0,0 +1,45 @@
+/* Any copyright is dedicated to the public domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+// Bug 795317: Test that the browser element sanitizes its URIs by removing the
+// "unexposable" parts before sending them in the locationchange event.
+
+"use strict";
+
+/* global browserElementTestHelpers */
+
+SimpleTest.waitForExplicitFinish();
+browserElementTestHelpers.setEnabledPref(true);
+browserElementTestHelpers.addPermission();
+
+var iframe;
+
+function testPassword() {
+  function locationchange(e) {
+    var uri = e.detail.url;
+    is(
+      uri,
+      "http://mochi.test:8888/tests/dom/browser-element/mochitest/file_empty.html",
+      "Username and password shouldn't be exposed in uri."
+    );
+    SimpleTest.finish();
+  }
+
+  iframe.addEventListener("mozbrowserlocationchange", locationchange);
+  iframe.src =
+    "http://iamuser:iampassword@mochi.test:8888/tests/dom/browser-element/mochitest/file_empty.html";
+}
+
+function runTest() {
+  SpecialPowers.pushPrefEnv(
+    { set: [["network.http.rcwn.enabled", false]] },
+    _ => {
+      iframe = document.createElement("iframe");
+      iframe.setAttribute("mozbrowser", "true");
+      document.body.appendChild(iframe);
+      testPassword();
+    }
+  );
+}
+
+addEventListener("testready", runTest);
diff --git a/dom/browser-element/mochitest/browserElement_FirstPaint.js b/dom/browser-element/mochitest/browserElement_FirstPaint.js
new file mode 100644
index 000000000000..57317d83e22e
--- /dev/null
+++ b/dom/browser-element/mochitest/browserElement_FirstPaint.js
@@ -0,0 +1,44 @@
+/* Any copyright is dedicated to the public domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+// Bug 787378 - Add mozbrowserfirstpaint event.
+"use strict";
+
+/* global browserElementTestHelpers */
+
+SimpleTest.waitForExplicitFinish();
+browserElementTestHelpers.setEnabledPref(true);
+browserElementTestHelpers.addPermission();
+
+function runTest() {
+  var iframe = document.createElement("iframe");
+  iframe.setAttribute("mozbrowser", "true");
+
+  var gotFirstPaint = false;
+  var gotFirstLocationChange = false;
+  iframe.addEventListener("mozbrowserfirstpaint", function(e) {
+    ok(!gotFirstPaint, "Got only one first paint.");
+    gotFirstPaint = true;
+
+    if (gotFirstLocationChange) {
+      iframe.src = browserElementTestHelpers.emptyPage1 + "?2";
+    }
+  });
+
+  iframe.addEventListener("mozbrowserlocationchange", function(e) {
+    if (e.detail.url == browserElementTestHelpers.emptyPage1) {
+      gotFirstLocationChange = true;
+      if (gotFirstPaint) {
+        iframe.src = browserElementTestHelpers.emptyPage1 + "?2";
+      }
+    } else if (e.detail.url.endsWith("?2")) {
+      SimpleTest.finish();
+    }
+  });
+
+  document.body.appendChild(iframe);
+
+  iframe.src = browserElementTestHelpers.emptyPage1;
+}
+
+addEventListener("testready", runTest);
diff --git a/dom/browser-element/mochitest/browserElement_ForwardName.js b/dom/browser-element/mochitest/browserElement_ForwardName.js
new file mode 100644
index 000000000000..5ff7dda78fdd
--- /dev/null
+++ b/dom/browser-element/mochitest/browserElement_ForwardName.js
@@ -0,0 +1,41 @@
+/* Any copyright is dedicated to the public domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+// Bug 781320 - Test that the name in <iframe mozbrowser name="foo"> is
+// forwarded down to remote mozbrowsers.
+
+"use strict";
+
+/* global browserElementTestHelpers */
+
+SimpleTest.waitForExplicitFinish();
+browserElementTestHelpers.setEnabledPref(true);
+browserElementTestHelpers.addPermission();
+
+function runTest() {
+  var iframe = document.createElement("iframe");
+  iframe.setAttribute("mozbrowser", "true");
+  iframe.setAttribute("name", "foo");
+
+  iframe.addEventListener("mozbrowserlocationchange", function(e) {
+    ok(true, "Got locationchange to " + e.detail.url);
+    if (e.detail.url.endsWith("ForwardName.html#finish")) {
+      SimpleTest.finish();
+    }
+  });
+
+  // The file sends us messages via alert() that start with "success:" or
+  // "failure:".
+  iframe.addEventListener("mozbrowsershowmodalprompt", function(e) {
+    ok(e.detail.message.startsWith("success:"), e.detail.message);
+  });
+
+  document.body.appendChild(iframe);
+
+  // This file does window.open('file_browserElement_ForwardName.html#finish',
+  // 'foo');  That should open in the curent window, because the window should
+  // be named foo.
+  iframe.src = "file_browserElement_ForwardName.html";
+}
+
+addEventListener("testready", runTest);
diff --git a/dom/browser-element/mochitest/browserElement_Iconchange.js b/dom/browser-element/mochitest/browserElement_Iconchange.js
new file mode 100644
index 000000000000..15b6560bb038
--- /dev/null
+++ b/dom/browser-element/mochitest/browserElement_Iconchange.js
@@ -0,0 +1,139 @@
+/* Any copyright is dedicated to the public domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+// Test that the onmozbrowsericonchange event works.
+"use strict";
+
+/* global browserElementTestHelpers */
+
+SimpleTest.waitForExplicitFinish();
+browserElementTestHelpers.setEnabledPref(true);
+browserElementTestHelpers.addPermission();
+browserElementTestHelpers.allowTopLevelDataURINavigation();
+
+function createHtml(link) {
+  return "data:text/html,<html><head>" + link + "<body></body></html>";
+}
+
+function createLink(name, sizes, rel) {
+  var s = sizes ? 'sizes="' + sizes + '"' : "";
+  if (!rel) {
+    rel = "icon";
+  }
+  return (
+    '<link rel="' +
+    rel +
+    '" type="image/png" ' +
+    s +
+    ' href="http://example.com/' +
+    name +
+    '.png">'
+  );
+}
+
+function runTest() {
+  var iframe1 = document.createElement("iframe");
+  iframe1.setAttribute("mozbrowser", "true");
+  document.body.appendChild(iframe1);
+
+  // iframe2 is a red herring; we modify its favicon but don't listen for
+  // iconchanges; we want to make sure that its iconchange events aren't
+  // picked up by the listener on iframe1.
+  var iframe2 = document.createElement("iframe");
+  iframe2.setAttribute("mozbrowser", "true");
+  document.body.appendChild(iframe2);
+
+  // iframe3 is another red herring.  It's not a mozbrowser, so we shouldn't
+  // get any iconchange events on it.
+  var iframe3 = document.createElement("iframe");
+  document.body.appendChild(iframe3);
+
+  var numIconChanges = 0;
+
+  iframe1.addEventListener("mozbrowsericonchange", function(e) {
+    numIconChanges++;
+
+    if (numIconChanges == 1) {
+      is(e.detail.href, "http://example.com/myicon.png");
+
+      // We should recieve iconchange events when the user creates new links
+      // to a favicon, but only when we listen for them
+      SpecialPowers.getBrowserFrameMessageManager(iframe1).loadFrameScript(
+        "data:,content.document.title='New title';",
+        /* allowDelayedLoad = */ false
+      );
+
+      SpecialPowers.getBrowserFrameMessageManager(iframe1).loadFrameScript(
+        "data:,content.document.head.insertAdjacentHTML('beforeend', '<link rel=ICON href=http://example.com/newicon.png>')",
+        /* allowDelayedLoad = */ false
+      );
+
+      SpecialPowers.getBrowserFrameMessageManager(iframe2).loadFrameScript(
+        "data:,content.document.head.insertAdjacentHTML('beforeend', '<link rel=ICON href=http://example.com/newicon.png>')",
+        /* allowDelayedLoad = */ false
+      );
+    } else if (numIconChanges == 2) {
+      is(e.detail.href, "http://example.com/newicon.png");
+
+      // Full new pages should trigger iconchange events
+      iframe1.src = createHtml(createLink("3rdicon"));
+    } else if (numIconChanges == 3) {
+      is(e.detail.href, "http://example.com/3rdicon.png");
+
+      // the rel attribute can have various space seperated values, make
+      // sure we only pick up correct values for 'icon'
+      SpecialPowers.getBrowserFrameMessageManager(iframe1).loadFrameScript(
+        "data:,content.document.head.insertAdjacentHTML('beforeend', '<link rel=shortcuticon href=http://example.com/newicon.png>')",
+        /* allowDelayedLoad = */ false
+      );
+      // Test setting a page with multiple links elements
+      iframe1.src = createHtml(createLink("another") + createLink("icon"));
+    } else if (numIconChanges == 4) {
+      is(e.detail.href, "http://example.com/another.png");
+      // 2 events will be triggered by previous test, wait for next
+    } else if (numIconChanges == 5) {
+      is(e.detail.href, "http://example.com/icon.png");
+
+      // Make sure icon check is case insensitive
+      SpecialPowers.getBrowserFrameMessageManager(iframe1).loadFrameScript(
+        "data:,content.document.head.insertAdjacentHTML('beforeend', '<link rel=ICON href=http://example.com/ucaseicon.png>')",
+        /* allowDelayedLoad = */ false
+      );
+    } else if (numIconChanges == 6) {
+      is(e.detail.href, "http://example.com/ucaseicon.png");
+      iframe1.src = createHtml(createLink("testsize", "50x50", "icon"));
+    } else if (numIconChanges == 7) {
+      is(e.detail.href, "http://example.com/testsize.png");
+      is(e.detail.sizes, "50x50");
+      iframe1.src = createHtml(
+        createLink("testapple1", "100x100", "apple-touch-icon")
+      );
+    } else if (numIconChanges == 8) {
+      is(e.detail.href, "http://example.com/testapple1.png");
+      is(e.detail.rel, "apple-touch-icon");
+      is(e.detail.sizes, "100x100");
+
+      iframe1.src = createHtml(
+        createLink("testapple2", "100x100", "apple-touch-icon-precomposed")
+      );
+    } else if (numIconChanges == 9) {
+      is(e.detail.href, "http://example.com/testapple2.png");
+      is(e.detail.rel, "apple-touch-icon-precomposed");
+      is(e.detail.sizes, "100x100");
+      SimpleTest.finish();
+    } else {
+      ok(false, "Too many iconchange events.");
+    }
+  });
+
+  iframe3.addEventListener("mozbrowsericonchange", function(e) {
+    ok(false, "Should not get a iconchange event for iframe3.");
+  });
+
+  iframe1.src = createHtml(createLink("myicon"));
+  // We should not recieve icon change events for either of the below iframes
+  iframe2.src = createHtml(createLink("myicon"));
+  iframe3.src = createHtml(createLink("myicon"));
+}
+
+addEventListener("testready", runTest);
diff --git a/dom/browser-element/mochitest/browserElement_LoadEvents.js b/dom/browser-element/mochitest/browserElement_LoadEvents.js
new file mode 100644
index 000000000000..9780c9d3e425
--- /dev/null
+++ b/dom/browser-element/mochitest/browserElement_LoadEvents.js
@@ -0,0 +1,144 @@
+/* Any copyright is dedicated to the public domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+// Test that an iframe with the |mozbrowser| attribute emits mozbrowserloadX
+// events when this page is in the whitelist.
+
+"use strict";
+
+/* global browserElementTestHelpers */
+
+SimpleTest.waitForExplicitFinish();
+browserElementTestHelpers.setEnabledPref(true);
+browserElementTestHelpers.addPermission();
+
+function runTest() {
+  // Load emptypage1 into the iframe, wait for that to finish loading, then
+  // call runTest2.
+  //
+  // This should trigger loadstart, locationchange, and loadend events.
+
+  var seenLoadEnd = false;
+  var seenLoadStart = false;
+  var seenLocationChange = false;
+
+  var iframe = document.createElement("iframe");
+  iframe.setAttribute("mozbrowser", "true");
+  iframe.id = "iframe";
+  iframe.src =
+    "http://example.com/tests/dom/browser-element/mochitest/file_browserElement_LoadEvents.html";
+
+  function loadstart(e) {
+    ok(e.isTrusted, "Event should be trusted.");
+    ok(!seenLoadEnd, "loadstart before loadend.");
+    ok(!seenLoadStart, "Just one loadstart event.");
+    ok(!seenLocationChange, "loadstart before locationchange.");
+    seenLoadStart = true;
+  }
+
+  function locationchange(e) {
+    ok(e.isTrusted, "Event should be trusted.");
+    ok(!seenLocationChange, "Just one locationchange event.");
+    seenLocationChange = true;
+    ok(seenLoadStart, "Location change after load start.");
+    ok(!seenLoadEnd, "Location change before load end.");
+    // XXX: Switched to from ok() to todo_is() in Bug 1467712. Follow up in 1503862
+    // Fails with: event's reported location -
+    //   got "http://example.com/tests/dom/browser-element/mochitest/file_browserElement_LoadEvents.html",
+    //   expected "http://example.com/tests/dom/browser-element/mochitest/file_empty.html"
+    todo_is(
+      e.detail.url,
+      browserElementTestHelpers.emptyPage1,
+      "event's reported location"
+    );
+  }
+
+  function loadend(e) {
+    ok(e.isTrusted, "Event should be trusted.");
+    ok(seenLoadStart, "loadend after loadstart.");
+    ok(!seenLoadEnd, "Just one loadend event.");
+    ok(seenLocationChange, "loadend after locationchange.");
+    is(
+      e.detail.backgroundColor,
+      "rgb(0, 128, 0)",
+      "Expected background color reported"
+    );
+    seenLoadEnd = true;
+  }
+
+  iframe.addEventListener("mozbrowserloadstart", loadstart);
+  iframe.addEventListener("mozbrowserlocationchange", locationchange);
+  iframe.addEventListener("mozbrowserloadend", loadend);
+
+  function waitForAllCallbacks() {
+    if (!seenLoadStart || !seenLoadEnd) {
+      SimpleTest.executeSoon(waitForAllCallbacks);
+      return;
+    }
+
+    iframe.removeEventListener("mozbrowserloadstart", loadstart);
+    iframe.removeEventListener("mozbrowserlocationchange", locationchange);
+    iframe.removeEventListener("mozbrowserloadend", loadend);
+    runTest2();
+  }
+
+  document.body.appendChild(iframe);
+  waitForAllCallbacks();
+}
+
+function runTest2() {
+  var seenLoadStart = false;
+  var seenLoadEnd = false;
+  var seenLocationChange = false;
+
+  // Add this event listener to the document; the events should bubble.
+  document.addEventListener("mozbrowserloadstart", function(e) {
+    ok(e.isTrusted, "Event should be trusted.");
+    ok(!seenLoadStart, "Just one loadstart event.");
+    seenLoadStart = true;
+    ok(!seenLoadEnd, "Got mozbrowserloadstart before loadend.");
+    ok(!seenLocationChange, "Got mozbrowserloadstart before locationchange.");
+  });
+
+  var iframe = document.getElementById("iframe");
+  iframe.addEventListener("mozbrowserlocationchange", function(e) {
+    ok(e.isTrusted, "Event should be trusted.");
+    ok(!seenLocationChange, "Just one locationchange event.");
+    seenLocationChange = true;
+    ok(seenLoadStart, "Location change after load start.");
+    ok(!seenLoadEnd, "Location change before load end.");
+    is(
+      e.detail.url,
+      browserElementTestHelpers.emptyPage2,
+      "event's reported location"
+    );
+  });
+
+  iframe.addEventListener("mozbrowserloadend", function(e) {
+    ok(e.isTrusted, "Event should be trusted.");
+    ok(!seenLoadEnd, "Just one load end event.");
+    seenLoadEnd = true;
+    ok(seenLoadStart, "Load end after load start.");
+    ok(seenLocationChange, "Load end after location change.");
+    is(
+      e.detail.backgroundColor,
+      "rgba(0, 0, 0, 0)",
+      "Expected background color reported"
+    );
+  });
+
+  iframe.src = browserElementTestHelpers.emptyPage2;
+
+  function waitForAllCallbacks() {
+    if (!seenLoadStart || !seenLoadEnd || !seenLocationChange) {
+      SimpleTest.executeSoon(waitForAllCallbacks);
+      return;
+    }
+
+    SimpleTest.finish();
+  }
+
+  waitForAllCallbacks();
+}
+
+addEventListener("testready", runTest);
diff --git a/dom/browser-element/mochitest/browserElement_Metachange.js b/dom/browser-element/mochitest/browserElement_Metachange.js
new file mode 100644
index 000000000000..f8900fad7c6b
--- /dev/null
+++ b/dom/browser-element/mochitest/browserElement_Metachange.js
@@ -0,0 +1,198 @@
+/* Any copyright is dedicated to the public domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+// Test that the onmozbrowsermetachange event works.
+"use strict";
+
+/* global browserElementTestHelpers */
+
+SimpleTest.waitForExplicitFinish();
+browserElementTestHelpers.setEnabledPref(true);
+browserElementTestHelpers.addPermission();
+browserElementTestHelpers.allowTopLevelDataURINavigation();
+
+function createHtml(meta) {
+  return (
+    'data:text/html,<html xmlns:xml="http://www.w3.org/XML/1998/namespace"><head>' +
+    meta +
+    "<body></body></html>"
+  );
+}
+
+function createHtmlWithLang(meta, lang) {
+  return (
+    'data:text/html,<html xmlns:xml="http://www.w3.org/XML/1998/namespace" lang="' +
+    lang +
+    '"><head>' +
+    meta +
+    "<body></body></html>"
+  );
+}
+
+function createMeta(name, content) {
+  return '<meta name="' + name + '" content="' + content + '">';
+}
+
+function createMetaWithLang(name, content, lang) {
+  return (
+    '<meta name="' + name + '" content="' + content + '" lang="' + lang + '">'
+  );
+}
+
+function createMetaWithProperty(property, content) {
+  return '<meta property="' + property + '" content="' + content + '">';
+}
+
+function runTest() {
+  var iframe1 = document.createElement("iframe");
+  iframe1.setAttribute("mozbrowser", "true");
+  document.body.appendChild(iframe1);
+
+  // iframe2 is a red herring; we modify its meta elements but don't listen for
+  // metachanges; we want to make sure that its metachange events aren't
+  // picked up by the listener on iframe1.
+  var iframe2 = document.createElement("iframe");
+  iframe2.setAttribute("mozbrowser", "true");
+  document.body.appendChild(iframe2);
+
+  // iframe3 is another red herring.  It's not a mozbrowser, so we shouldn't
+  // get any metachange events on it.
+  var iframe3 = document.createElement("iframe");
+  document.body.appendChild(iframe3);
+
+  var numMetaChanges = 0;
+
+  iframe1.addEventListener("mozbrowsermetachange", function(e) {
+    numMetaChanges++;
+
+    if (numMetaChanges == 1) {
+      is(e.detail.name, "application-name");
+      is(e.detail.content, "foobar");
+
+      // We should recieve metachange events when the user creates new metas
+      SpecialPowers.getBrowserFrameMessageManager(iframe1).loadFrameScript(
+        "data:,content.document.title='New title';",
+        /* allowDelayedLoad = */ false
+      );
+
+      SpecialPowers.getBrowserFrameMessageManager(iframe1).loadFrameScript(
+        "data:,content.document.head.insertAdjacentHTML('beforeend', '<meta name=application-name content=new_foobar>')",
+        /* allowDelayedLoad = */ false
+      );
+
+      SpecialPowers.getBrowserFrameMessageManager(iframe2).loadFrameScript(
+        "data:,content.document.head.insertAdjacentHTML('beforeend', '<meta name=application-name content=new_foobar>')",
+        /* allowDelayedLoad = */ false
+      );
+    } else if (numMetaChanges == 2) {
+      is(e.detail.name, "application-name", "name matches");
+      is(e.detail.content, "new_foobar", "content matches");
+      ok(!("lang" in e.detail), "lang not present");
+
+      // Full new pages should trigger metachange events
+      iframe1.src = createHtml(createMeta("application-name", "3rd_foobar"));
+    } else if (numMetaChanges == 3) {
+      is(e.detail.name, "application-name", "name matches");
+      is(e.detail.content, "3rd_foobar", "content matches");
+      ok(!("lang" in e.detail), "lang not present");
+
+      // Test setting a page with multiple meta elements
+      iframe1.src = createHtml(
+        createMeta("application-name", "foobar_1") +
+          createMeta("application-name", "foobar_2")
+      );
+    } else if (numMetaChanges == 4) {
+      is(e.detail.name, "application-name", "name matches");
+      is(e.detail.content, "foobar_1", "content matches");
+      ok(!("lang" in e.detail), "lang not present");
+      // 2 events will be triggered by previous test, wait for next
+    } else if (numMetaChanges == 5) {
+      is(e.detail.name, "application-name", "name matches");
+      is(e.detail.content, "foobar_2", "content matches");
+      ok(!("lang" in e.detail), "lang not present");
+
+      // Test the language
+      iframe1.src = createHtml(
+        createMetaWithLang("application-name", "foobar_lang_1", "en")
+      );
+    } else if (numMetaChanges == 6) {
+      is(e.detail.name, "application-name", "name matches");
+      is(e.detail.content, "foobar_lang_1", "content matches");
+      is(e.detail.lang, "en", "language matches");
+
+      // Test the language in the ancestor element
+      iframe1.src = createHtmlWithLang(
+        createMeta("application-name", "foobar_lang_2"),
+        "es"
+      );
+    } else if (numMetaChanges == 7) {
+      is(e.detail.name, "application-name", "name matches");
+      is(e.detail.content, "foobar_lang_2", "content matches");
+      is(e.detail.lang, "es", "language matches");
+
+      // Test the language in the ancestor element
+      iframe1.src = createHtmlWithLang(
+        createMetaWithLang("application-name", "foobar_lang_3", "it"),
+        "fi"
+      );
+    } else if (numMetaChanges == 8) {
+      is(e.detail.name, "application-name", "name matches");
+      is(e.detail.content, "foobar_lang_3", "content matches");
+      is(e.detail.lang, "it", "language matches");
+
+      // Test the content-language
+      iframe1.src =
+        "http://test/tests/dom/browser-element/mochitest/file_browserElement_Metachange.sjs?ru";
+    } else if (numMetaChanges == 9) {
+      is(e.detail.name, "application-name", "name matches");
+      is(e.detail.content, "sjs", "content matches");
+      is(e.detail.lang, "ru", "language matches");
+
+      // Test the content-language
+      iframe1.src =
+        "http://test/tests/dom/browser-element/mochitest/file_browserElement_Metachange.sjs?ru|dk";
+    } else if (numMetaChanges == 10) {
+      is(e.detail.name, "application-name", "name matches");
+      is(e.detail.content, "sjs", "content matches");
+      is(e.detail.lang, "dk", "language matches");
+
+      // Test Open Graph property
+      iframe1.src = createHtml(
+        createMetaWithProperty("og:description", "Fascinating article")
+      );
+
+      // We should not get event if property doesn't start with 'og:'
+      iframe3.src = createHtml(
+        createMetaWithProperty("go:description", "Fascinating article")
+      );
+    } else if (numMetaChanges == 11) {
+      is(e.detail.name, "og:description", "property name matches");
+      is(e.detail.content, "Fascinating article", "content matches");
+
+      // Sometimes 'name' is used instead of 'property'. Verify that works.
+      iframe1.src = createHtml(createMeta("og:title", "One weird trick!"));
+
+      // We should not get event if property doesn't start with 'og:'
+      iframe3.src = createHtml(createMeta("go:title", "One weird trick!"));
+    } else if (numMetaChanges == 12) {
+      is(e.detail.name, "og:title", "property name matches");
+      is(e.detail.content, "One weird trick!", "content matches");
+
+      // Test the language
+      SimpleTest.finish();
+    } else {
+      ok(false, "Too many metachange events.");
+    }
+  });
+
+  iframe3.addEventListener("mozbrowsermetachange", function(e) {
+    ok(false, "Should not get a metachange event for iframe3.");
+  });
+
+  iframe1.src = createHtml(createMeta("application-name", "foobar"));
+  // We should not recieve meta change events for either of the below iframes
+  iframe2.src = createHtml(createMeta("application-name", "foobar"));
+  iframe3.src = createHtml(createMeta("application-name", "foobar"));
+}
+
+addEventListener("testready", runTest);
diff --git a/dom/browser-element/mochitest/browserElement_Opensearch.js b/dom/browser-element/mochitest/browserElement_Opensearch.js
new file mode 100644
index 000000000000..663adcc19ed6
--- /dev/null
+++ b/dom/browser-element/mochitest/browserElement_Opensearch.js
@@ -0,0 +1,113 @@
+/* Any copyright is dedicated to the public domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+// Test that the onmozbrowseropensearch event works.
+"use strict";
+
+/* global browserElementTestHelpers */
+
+SimpleTest.waitForExplicitFinish();
+browserElementTestHelpers.setEnabledPref(true);
+browserElementTestHelpers.addPermission();
+browserElementTestHelpers.allowTopLevelDataURINavigation();
+
+function createHtml(link) {
+  return "data:text/html,<html><head>" + link + "<body></body></html>";
+}
+
+function createLink(name) {
+  return (
+    '<link rel="search" title="Test OpenSearch" type="application/opensearchdescription+xml" href="http://example.com/' +
+    name +
+    '.xml">'
+  );
+}
+
+function runTest() {
+  var iframe1 = document.createElement("iframe");
+  iframe1.setAttribute("mozbrowser", "true");
+  document.body.appendChild(iframe1);
+
+  // iframe2 is a red herring; we modify its link but don't listen for
+  // opensearch; we want to make sure that its opensearch events aren't
+  // picked up by the listener on iframe1.
+  var iframe2 = document.createElement("iframe");
+  iframe2.setAttribute("mozbrowser", "true");
+  document.body.appendChild(iframe2);
+
+  // iframe3 is another red herring.  It's not a mozbrowser, so we shouldn't
+  // get any opensearch events on it.
+  var iframe3 = document.createElement("iframe");
+  document.body.appendChild(iframe3);
+
+  var numLinkChanges = 0;
+
+  iframe1.addEventListener("mozbrowseropensearch", function(e) {
+    numLinkChanges++;
+
+    if (numLinkChanges == 1) {
+      is(e.detail.title, "Test OpenSearch");
+      is(e.detail.href, "http://example.com/mysearch.xml");
+
+      // We should recieve opensearch events when the user creates new links
+      // to a search engine, but only when we listen for them
+      SpecialPowers.getBrowserFrameMessageManager(iframe1).loadFrameScript(
+        "data:,content.document.title='New title';",
+        /* allowDelayedLoad = */ false
+      );
+
+      SpecialPowers.getBrowserFrameMessageManager(iframe1).loadFrameScript(
+        "data:,content.document.head.insertAdjacentHTML('beforeend', '<link rel=SEARCH type=application/opensearchdescription+xml href=http://example.com/newsearch.xml>')",
+        /* allowDelayedLoad = */ false
+      );
+
+      SpecialPowers.getBrowserFrameMessageManager(iframe2).loadFrameScript(
+        "data:,content.document.head.insertAdjacentHTML('beforeend', '<link rel=SEARCH type=application/opensearchdescription+xml href=http://example.com/newsearch.xml>')",
+        /* allowDelayedLoad = */ false
+      );
+    } else if (numLinkChanges == 2) {
+      is(e.detail.href, "http://example.com/newsearch.xml");
+
+      // Full new pages should trigger opensearch events
+      iframe1.src = createHtml(createLink("3rdsearch"));
+    } else if (numLinkChanges == 3) {
+      is(e.detail.href, "http://example.com/3rdsearch.xml");
+
+      // the rel attribute can have various space seperated values, make
+      // sure we only pick up correct values for 'opensearch'
+      SpecialPowers.getBrowserFrameMessageManager(iframe1).loadFrameScript(
+        "data:,content.document.head.insertAdjacentHTML('beforeend', '<link rel=someopensearch type=application/opensearchdescription+xml href=http://example.com/newsearch.xml>')",
+        /* allowDelayedLoad = */ false
+      );
+      // Test setting a page with multiple links elements
+      iframe1.src = createHtml(createLink("another") + createLink("search"));
+    } else if (numLinkChanges == 4) {
+      is(e.detail.href, "http://example.com/another.xml");
+      // 2 events will be triggered by previous test, wait for next
+    } else if (numLinkChanges == 5) {
+      is(e.detail.href, "http://example.com/search.xml");
+
+      // Make sure opensearch check is case insensitive
+      SpecialPowers.getBrowserFrameMessageManager(iframe1).loadFrameScript(
+        "data:,content.document.head.insertAdjacentHTML('beforeend', '<link rel=SEARCH type=application/opensearchdescription+xml href=http://example.com/ucasesearch.xml>')",
+        /* allowDelayedLoad = */ false
+      );
+    } else if (numLinkChanges == 6) {
+      is(e.detail.href, "http://example.com/ucasesearch.xml");
+      SimpleTest.finish();
+    } else {
+      ok(false, "Too many opensearch events.");
+    }
+  });
+
+  iframe3.addEventListener("mozbrowseropensearch", function(e) {
+    ok(false, "Should not get a opensearch event for iframe3.");
+  });
+
+  iframe1.src = createHtml(createLink("mysearch"));
+  // We should not recieve opensearch change events for either of the below iframes
+  iframe2.src = createHtml(createLink("mysearch"));
+  iframe3.src = createHtml(createLink("mysearch"));
+}
+
+addEventListener("testready", runTest);
diff --git a/dom/browser-element/mochitest/browserElement_PrivateBrowsing.js b/dom/browser-element/mochitest/browserElement_PrivateBrowsing.js
new file mode 100644
index 000000000000..474bce46c99e
--- /dev/null
+++ b/dom/browser-element/mochitest/browserElement_PrivateBrowsing.js
@@ -0,0 +1,56 @@
+/* Any copyright is dedicated to the public domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+// Test that the mozprivatebrowsing attribute works.
+"use strict";
+
+/* global browserElementTestHelpers */
+
+SimpleTest.waitForExplicitFinish();
+browserElementTestHelpers.setEnabledPref(true);
+browserElementTestHelpers.addPermission();
+
+function createFrame(aIsPrivate) {
+  var iframe = document.createElement("iframe");
+  iframe.setAttribute("mozbrowser", "true");
+  if (aIsPrivate) {
+    iframe.setAttribute("mozprivatebrowsing", "true");
+  }
+  return iframe;
+}
+
+function createTest(aIsPrivate, aExpected, aClearStorage) {
+  info("createTest " + aIsPrivate + " " + aExpected);
+  return new Promise(function(resolve, reject) {
+    var iframe = createFrame(aIsPrivate);
+    document.body.appendChild(iframe);
+
+    iframe.addEventListener("mozbrowsershowmodalprompt", function(e) {
+      is(e.detail.message, aExpected, "Checking localstorage");
+      resolve();
+    });
+
+    var src = "file_browserElement_PrivateBrowsing.html";
+    iframe.src = aClearStorage ? src + "?clear=true" : src;
+  });
+}
+
+function runTest() {
+  // We first create a iframe in non private browsing mode, set up some
+  // localstorage, reopen it to check that we get the previously set value.
+  // Finally, open it in private browsing mode and check that localstorage
+  // is clear.
+  createTest(false, "CLEAR", true)
+    .then(() => {
+      return createTest(false, "EMPTY", false);
+    })
+    .then(() => {
+      return createTest(false, "bar", false);
+    })
+    .then(() => {
+      return createTest(true, "EMPTY", false);
+    })
+    .then(SimpleTest.finish);
+}
+
+addEventListener("testready", runTest);
diff --git a/dom/browser-element/mochitest/browserElement_PromptCheck.js b/dom/browser-element/mochitest/browserElement_PromptCheck.js
new file mode 100644
index 000000000000..a8d0f269f971
--- /dev/null
+++ b/dom/browser-element/mochitest/browserElement_PromptCheck.js
@@ -0,0 +1,65 @@
+/* Any copyright is dedicated to the public domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+// Test that alertCheck (i.e., alert with the opportunity to opt out of future
+// alerts), promptCheck, and confirmCheck work.  We do this by spamming
+// alerts/prompts/confirms from inside an <iframe mozbrowser>.
+//
+// At the moment, we treat alertCheck/promptCheck/confirmCheck just like a
+// normal alert.  But it's different to nsIPrompt!
+
+"use strict";
+
+/* global browserElementTestHelpers */
+
+SimpleTest.waitForExplicitFinish();
+browserElementTestHelpers.setEnabledPref(true);
+browserElementTestHelpers.addPermission();
+browserElementTestHelpers.allowTopLevelDataURINavigation();
+
+function runTest() {
+  var iframe = document.createElement("iframe");
+  iframe.setAttribute("mozbrowser", "true");
+  document.body.appendChild(iframe);
+
+  var numPrompts = 0;
+  iframe.addEventListener("mozbrowsershowmodalprompt", function(e) {
+    is(e.detail.message, String(numPrompts), "prompt message");
+    if (numPrompts / 10 < 1) {
+      is(e.detail.promptType, "alert");
+    } else if (numPrompts / 10 < 2) {
+      is(e.detail.promptType, "confirm");
+    } else {
+      is(e.detail.promptType, "prompt");
+    }
+
+    numPrompts++;
+    if (numPrompts == 30) {
+      SimpleTest.finish();
+    }
+  });
+
+  /* eslint-disable no-useless-concat */
+  iframe.src =
+    'data:text/html,<html><body><script>\
+      addEventListener("load", function() { \
+       setTimeout(function() { \
+        var i = 0; \
+        for (; i < 10; i++) { alert(i); } \
+        for (; i < 20; i++) { confirm(i); } \
+        for (; i < 30; i++) { prompt(i); } \
+       }); \
+     }); \
+     </scr' +
+    "ipt></body></html>";
+  /* eslint-enable no-useless-concat */
+}
+
+// The test harness sets dom.successive_dialog_time_limit to 0 for some bizarre
+// reason.  That's not normal usage, and it keeps us from testing alertCheck!
+addEventListener("testready", function() {
+  SpecialPowers.pushPrefEnv(
+    { set: [["dom.successive_dialog_time_limit", 10]] },
+    runTest
+  );
+});
diff --git a/dom/browser-element/mochitest/browserElement_PromptConfirm.js b/dom/browser-element/mochitest/browserElement_PromptConfirm.js
new file mode 100644
index 000000000000..13c67a7079ec
--- /dev/null
+++ b/dom/browser-element/mochitest/browserElement_PromptConfirm.js
@@ -0,0 +1,99 @@
+/* Any copyright is dedicated to the public domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+// Test that prompt and confirm work.  In particular, we're concerned that we
+// get correct return values out of them.
+//
+// We use alert() to communicate the return values of prompt/confirm back to
+// ourselves.
+"use strict";
+
+/* global browserElementTestHelpers */
+
+SimpleTest.waitForExplicitFinish();
+browserElementTestHelpers.setEnabledPref(true);
+browserElementTestHelpers.addPermission();
+browserElementTestHelpers.allowTopLevelDataURINavigation();
+
+function runTest() {
+  var iframe = document.createElement("iframe");
+  iframe.setAttribute("mozbrowser", "true");
+  document.body.appendChild(iframe);
+
+  var prompts = [
+    { msg: "1", type: "alert", rv: 42, expected: "undefined" },
+    { msg: "2", type: "confirm", rv: true, expected: "true" },
+    { msg: "3", type: "confirm", rv: false, expected: "false" },
+
+    // rv == 42 should be coerced to 'true' for confirm.
+    { msg: "4", type: "confirm", rv: 42, expected: "true" },
+    { msg: "5", type: "prompt", rv: "worked", expected: "worked" },
+    { msg: "6", type: "prompt", rv: null, expected: "null" },
+    { msg: "7", type: "prompt", rv: "", expected: "" },
+  ];
+
+  iframe.addEventListener("mozbrowsershowmodalprompt", function(e) {
+    var curPrompt = prompts[0];
+    if (!curPrompt.waitingForResponse) {
+      curPrompt.waitingForResponse = true;
+
+      is(e.detail.message, curPrompt.msg, "prompt message");
+      is(e.detail.promptType, curPrompt.type, "prompt type");
+
+      if (e.detail.promptType == "prompt") {
+        ok(
+          e.detail.returnValue === null,
+          "prompt's returnValue should be null"
+        );
+        is(e.detail.initialValue, "initial", "prompt's initial value.");
+      } else {
+        ok(
+          e.detail.returnValue === undefined,
+          "Other than for prompt, shouldn't have initial value."
+        );
+      }
+
+      // Block the child until we call e.detail.unblock().
+      e.preventDefault();
+
+      SimpleTest.executeSoon(function() {
+        e.detail.returnValue = curPrompt.rv;
+        e.detail.unblock();
+      });
+    } else {
+      prompts.shift();
+
+      // |e| now corresponds to an alert() containing the return value we just
+      // sent for this prompt.
+
+      is(
+        e.detail.message,
+        "RESULT:" + curPrompt.expected,
+        "expected rv for msg " + curPrompt.msg
+      );
+
+      if (prompts.length == 0) {
+        SimpleTest.finish();
+      }
+    }
+  });
+
+  /* eslint-disable no-useless-concat */
+  iframe.src =
+    'data:text/html,<html><body><script>\
+      function sendVal(val) { \
+        alert("RESULT:" + val); \
+      } \
+      sendVal(alert("1")); \
+      sendVal(confirm("2")); \
+      sendVal(confirm("3")); \
+      sendVal(confirm("4")); \
+      sendVal(prompt("5", "initial")); \
+      sendVal(prompt("6", "initial")); \
+      sendVal(prompt("7", "initial")); \
+    </scr' +
+    "ipt></body></html>";
+  /* eslint-enable no-useless-concat */
+}
+
+addEventListener("testready", runTest);
diff --git a/dom/browser-element/mochitest/browserElement_Reload.js b/dom/browser-element/mochitest/browserElement_Reload.js
new file mode 100644
index 000000000000..1ab8724e1837
--- /dev/null
+++ b/dom/browser-element/mochitest/browserElement_Reload.js
@@ -0,0 +1,63 @@
+/* Any copyright is dedicated to the public domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+// Bug 741717 - Test the reload ability of <iframe mozbrowser>.
+
+"use strict";
+
+/* global browserElementTestHelpers */
+/* eslint-env mozilla/frame-script */
+
+SimpleTest.waitForExplicitFinish();
+browserElementTestHelpers.setEnabledPref(true);
+browserElementTestHelpers.addPermission();
+
+var iframeScript = function() {
+  sendAsyncMessage("test:innerHTML", {
+    data: XPCNativeWrapper.unwrap(content).document.body.innerHTML,
+  });
+};
+
+var mm;
+var iframe;
+var loadedEvents = 0;
+var countAcc;
+
+function runTest() {
+  iframe = document.createElement("iframe");
+  iframe.setAttribute("mozbrowser", "true");
+
+  iframe.addEventListener("mozbrowserloadend", mozbrowserLoaded);
+
+  iframe.src = "file_bug741717.sjs";
+  document.body.appendChild(iframe);
+}
+
+function iframeBodyRecv(data) {
+  data = SpecialPowers.wrap(data);
+  var previousCount = countAcc;
+  var currentCount = parseInt(data.json.data, 10);
+  countAcc = currentCount;
+  switch (loadedEvents) {
+    case 1:
+      iframe.reload();
+      break;
+    case 2:
+      ok(true, "reload was triggered");
+      ok(previousCount === currentCount, "reload was a soft reload");
+      iframe.reload(true);
+      break;
+    case 3:
+      ok(currentCount > previousCount, "reload was a hard reload");
+      SimpleTest.finish();
+  }
+}
+
+function mozbrowserLoaded() {
+  loadedEvents++;
+  mm = SpecialPowers.getBrowserFrameMessageManager(iframe);
+  mm.addMessageListener("test:innerHTML", iframeBodyRecv);
+  mm.loadFrameScript("data:,(" + iframeScript.toString() + ")();", false);
+}
+
+addEventListener("testready", runTest);
diff --git a/dom/browser-element/mochitest/browserElement_ReloadPostRequest.js b/dom/browser-element/mochitest/browserElement_ReloadPostRequest.js
new file mode 100644
index 000000000000..ef5bdd676028
--- /dev/null
+++ b/dom/browser-element/mochitest/browserElement_ReloadPostRequest.js
@@ -0,0 +1,122 @@
+/* Any copyright is dedicated to the public domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+// Bug 793644, fire an event when attempting to reloads browser element after
+// POST respest.
+
+"use strict";
+
+/* global browserElementTestHelpers */
+
+SimpleTest.waitForExplicitFinish();
+SimpleTest.requestFlakyTimeout("untriaged");
+browserElementTestHelpers.setEnabledPref(true);
+
+var iframe;
+var gotConfirmRepost = false;
+var doRepost = true;
+var timer;
+var isPostRequestSubmitted;
+
+function getExpectedStrings() {
+  let result = {};
+  let appBundle = Services.strings.createBundle(
+    "chrome://global/locale/appstrings.properties"
+  );
+  let brandBundle = Services.strings.createBundle(
+    "chrome://branding/locale/brand.properties"
+  );
+  try {
+    let brandName = brandBundle.GetStringFromName("brandShortName");
+    result.message = appBundle.formatStringFromName("confirmRepostPrompt", [
+      brandName,
+    ]);
+  } catch (e) {
+    // for the case that we don't have brandShortName
+    result.message = appBundle.GetStringFromName("confirmRepostPrompt");
+  }
+  result.resend = appBundle.GetStringFromName("resendButton.label");
+
+  return result;
+}
+
+function failBecauseReloaded() {
+  window.clearTimeout(timer);
+  timer = null;
+  iframe.removeEventListener("mozbrowserloadend", failBecauseReloaded);
+  ok(false, "We don't expect browser element to reload, but it did");
+  SimpleTest.finish();
+}
+
+function reloadDone() {
+  iframe.removeEventListener("mozbrowserloadend", reloadDone);
+  ok(gotConfirmRepost, "Didn't get confirmEx prompt before reload");
+
+  // Run again, with repost disallowed.
+  doRepost = false;
+  isPostRequestSubmitted = false;
+  iframe.src = "file_post_request.html";
+  iframe.addEventListener("mozbrowserloadend", pageLoadDone);
+}
+
+function pageLoadDone() {
+  if (!isPostRequestSubmitted) {
+    // This loadend is done by setting url in address bar, so we don't need to
+    // do anything. The test page will submit a POST request.
+    isPostRequestSubmitted = true;
+    return;
+  }
+
+  gotConfirmRepost = false;
+  iframe.removeEventListener("mozbrowserloadend", pageLoadDone);
+  if (doRepost) {
+    iframe.addEventListener("mozbrowserloadend", reloadDone);
+  } else {
+    // We don't expect browserelement to reload; use a timer to make sure
+    // it is not reloaded.
+    iframe.addEventListener("mozbrowserloadend", failBecauseReloaded);
+  }
+  iframe.reload();
+}
+
+function runTest() {
+  iframe = document.createElement("iframe");
+  iframe.setAttribute("mozbrowser", "true");
+
+  isPostRequestSubmitted = false;
+  iframe.src = "file_post_request.html";
+  document.body.appendChild(iframe);
+
+  iframe.addEventListener("mozbrowserloadend", pageLoadDone);
+
+  let expectedMessage = getExpectedStrings();
+  iframe.addEventListener("mozbrowsershowmodalprompt", function(e) {
+    if (e.detail.promptType == "custom-prompt") {
+      gotConfirmRepost = true;
+      e.preventDefault();
+      e.detail.returnValue = {
+        selectedButton: doRepost ? 0 : 1,
+      };
+      is(e.detail.returnValue.checked, undefined);
+      is(e.detail.buttons[0].messageType, "custom");
+      is(e.detail.buttons[0].message, expectedMessage.resend);
+      is(e.detail.buttons[1].messageType, "builtin");
+      is(e.detail.buttons[1].message, "cancel");
+      is(e.detail.message, expectedMessage.message);
+      is(e.detail.buttons.length, 2);
+      is(e.detail.showCheckbox, false);
+      is(e.detail.checkboxMessage, null);
+      e.detail.unblock();
+
+      if (!doRepost) {
+        // To make sure the page doesn't reload in 1 sec.
+        timer = window.setTimeout(function() {
+          iframe.removeEventListener("mozbrowserloadend", failBecauseReloaded);
+          SimpleTest.finish();
+        }, 1000);
+      }
+    }
+  });
+}
+
+addEventListener("testready", runTest);
diff --git a/dom/browser-element/mochitest/browserElement_RemoveBrowserElement.js b/dom/browser-element/mochitest/browserElement_RemoveBrowserElement.js
new file mode 100644
index 000000000000..216abf7b5da1
--- /dev/null
+++ b/dom/browser-element/mochitest/browserElement_RemoveBrowserElement.js
@@ -0,0 +1,34 @@
+/* Any copyright is dedicated to the public domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+// Bug 787517: Remove iframe in the handler of showmodalprompt. This shouldn't
+// cause an exception to be thrown.
+
+"use strict";
+
+/* global browserElementTestHelpers */
+
+SimpleTest.waitForExplicitFinish();
+browserElementTestHelpers.setEnabledPref(true);
+browserElementTestHelpers.addPermission();
+browserElementTestHelpers.allowTopLevelDataURINavigation();
+
+function runTest() {
+  var iframe = document.createElement("iframe");
+  iframe.setAttribute("mozbrowser", "true");
+  document.body.appendChild(iframe);
+
+  iframe.addEventListener("mozbrowsershowmodalprompt", function(e) {
+    document.body.removeChild(iframe);
+    SimpleTest.executeSoon(function() {
+      ok(true);
+      SimpleTest.finish();
+    });
+  });
+
+  iframe.src =
+    'data:text/html,<html><body><script>alert("test")</script>' +
+    "</body></html>";
+}
+
+addEventListener("testready", runTest);
diff --git a/dom/browser-element/mochitest/browserElement_ScrollEvent.js b/dom/browser-element/mochitest/browserElement_ScrollEvent.js
new file mode 100644
index 000000000000..2db3e5e0770d
--- /dev/null
+++ b/dom/browser-element/mochitest/browserElement_ScrollEvent.js
@@ -0,0 +1,34 @@
+/* Any copyright is dedicated to the public domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+// Test that scroll event bubbles up.
+"use strict";
+
+/* global browserElementTestHelpers */
+
+SimpleTest.waitForExplicitFinish();
+browserElementTestHelpers.setEnabledPref(true);
+browserElementTestHelpers.addPermission();
+browserElementTestHelpers.allowTopLevelDataURINavigation();
+
+function runTest() {
+  var iframe = document.createElement("iframe");
+  iframe.setAttribute("mozbrowser", "true");
+  document.body.appendChild(iframe);
+
+  iframe.addEventListener("mozbrowserscroll", function(e) {
+    ok(true, "got mozbrowserscroll event.");
+    ok(e.detail, "event.detail is not null.");
+    is(Math.round(e.detail.top), 4000, "top position is correct.");
+    is(Math.round(e.detail.left), 4000, "left position is correct.");
+    SimpleTest.finish();
+  });
+
+  // We need a viewport meta tag to allow us to scroll to (4000, 4000). Without
+  // the viewport meta tag, we shrink the (5000, 5000) content so that we can't
+  // have enough space to scroll to the point in the layout viewport.
+  iframe.src =
+    "data:text/html,<html><meta name='viewport' content='width=device-width,minimum-scale=1,initial-scale=1'><body style='min-height: 5000px; min-width: 5000px;'></body><script>window.scrollTo(4000, 4000);</script></html>";
+}
+
+addEventListener("testready", runTest);
diff --git a/dom/browser-element/mochitest/browserElement_SecurityChange.js b/dom/browser-element/mochitest/browserElement_SecurityChange.js
new file mode 100644
index 000000000000..fff4ac15e9fe
--- /dev/null
+++ b/dom/browser-element/mochitest/browserElement_SecurityChange.js
@@ -0,0 +1,66 @@
+/* Any copyright is dedicated to the public domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+// Bug 763694 - Test that <iframe mozbrowser> delivers proper
+// mozbrowsersecuritychange events.
+
+"use strict";
+
+/* global browserElementTestHelpers */
+
+SimpleTest.waitForExplicitFinish();
+browserElementTestHelpers.setEnabledPref(true);
+browserElementTestHelpers.addPermission();
+
+function runTest() {
+  var iframe = document.createElement("iframe");
+  iframe.setAttribute("mozbrowser", "true");
+
+  var lastSecurityState;
+  iframe.addEventListener("mozbrowsersecuritychange", function(e) {
+    lastSecurityState = e.detail;
+  });
+
+  var filepath =
+    "tests/dom/browser-element/mochitest/file_browserElement_SecurityChange.html";
+
+  var count = 0;
+  iframe.addEventListener("mozbrowserloadend", function(e) {
+    count++;
+    switch (count) {
+      case 1:
+        is(lastSecurityState.state, "secure");
+        is(lastSecurityState.extendedValidation, false);
+        is(lastSecurityState.mixedContent, false);
+        iframe.src = "http://example.com/" + filepath;
+        break;
+      case 2:
+        is(lastSecurityState.state, "insecure");
+        is(lastSecurityState.extendedValidation, false);
+        is(lastSecurityState.mixedContent, false);
+        iframe.src = "https://example.com:443/" + filepath + "?broken";
+        break;
+      case 3:
+        is(lastSecurityState.state, "broken");
+        is(lastSecurityState.extendedValidation, false);
+        is(lastSecurityState.mixedContent, true);
+        SimpleTest.finish();
+        break;
+    }
+  });
+
+  iframe.src = "https://example.com/" + filepath;
+  document.body.appendChild(iframe);
+}
+
+addEventListener("testready", function() {
+  SpecialPowers.pushPrefEnv(
+    {
+      set: [
+        ["browser.safebrowsing.phishing.enabled", false],
+        ["browser.safebrowsing.malware.enabled", false],
+      ],
+    },
+    runTest
+  );
+});
diff --git a/dom/browser-element/mochitest/browserElement_SendEvent.js b/dom/browser-element/mochitest/browserElement_SendEvent.js
new file mode 100644
index 000000000000..e94fd31222a5
--- /dev/null
+++ b/dom/browser-element/mochitest/browserElement_SendEvent.js
@@ -0,0 +1,60 @@
+/* Any copyright is dedicated to the public domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+// Test that sendMouseEvent dispatch events.
+"use strict";
+
+/* global browserElementTestHelpers */
+
+SimpleTest.waitForExplicitFinish();
+browserElementTestHelpers.setEnabledPref(true);
+
+function runTest() {
+  var iframe = document.createElement("iframe");
+  iframe.setAttribute("mozbrowser", "true");
+  document.body.appendChild(iframe);
+  var x = 10;
+  var y = 10;
+  // This test used to try to transform the coordinates from child
+  // to parent coordinate space by first calling
+  // iframe.getBoundingClientRect();
+  // to refresh offsets and then calling
+  // var remoteTab = SpecialPowers.wrap(iframe)
+  //                .frameLoader.remoteTab;
+  // and calling remoteTab.getChildProcessOffset(offsetX, offsetY) if
+  // remoteTab was not null, but remoteTab was always null.
+
+  iframe.addEventListener("mozbrowserloadend", function onloadend(e) {
+    // Ensure we lay out the iframe before sending mouse events.
+    iframe.getBoundingClientRect();
+    iframe.sendMouseEvent("mousedown", x, y, 0, 1, 0);
+  });
+
+  iframe.addEventListener("mozbrowserlocationchange", function onlocchange(e) {
+    var a = document.createElement("a");
+    a.href = e.detail.url;
+
+    switch (a.hash) {
+      case "#mousedown":
+        ok(true, "Receive a mousedown event.");
+        iframe.sendMouseEvent("mousemove", x, y, 0, 0, 0);
+        break;
+      case "#mousemove":
+        ok(true, "Receive a mousemove event.");
+        iframe.sendMouseEvent("mouseup", x, y, 0, 1, 0);
+        break;
+      case "#mouseup":
+        ok(true, "Receive a mouseup event.");
+        break;
+      case "#click":
+        ok(true, "Receive a click event.");
+        iframe.removeEventListener("mozbrowserlocationchange", onlocchange);
+        SimpleTest.finish();
+        break;
+    }
+  });
+
+  iframe.src = "file_browserElement_SendEvent.html";
+}
+
+addEventListener("testready", runTest);
diff --git a/dom/browser-element/mochitest/browserElement_Stop.js b/dom/browser-element/mochitest/browserElement_Stop.js
new file mode 100644
index 000000000000..2d7fda410203
--- /dev/null
+++ b/dom/browser-element/mochitest/browserElement_Stop.js
@@ -0,0 +1,59 @@
+/* Any copyright is dedicated to the public domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+// Bug 709759 - Test the stop ability of <iframe mozbrowser>.
+
+// The img that is loaded will never be returned and will block
+// the page from loading, the timeout ensures that the page is
+// actually blocked from loading, once stop is called the
+// image load will be cancaelled and mozbrowserloadend should be called.
+
+"use strict";
+
+/* global browserElementTestHelpers */
+
+SimpleTest.waitForExplicitFinish();
+SimpleTest.requestFlakyTimeout("untriaged");
+browserElementTestHelpers.setEnabledPref(true);
+
+var iframe;
+var stopped = false;
+var imgSrc =
+  "http://test/tests/dom/browser-element/mochitest/file_bug709759.sjs";
+
+function runTest() {
+  iframe = document.createElement("iframe");
+  iframe.setAttribute("mozbrowser", "true");
+  // FIXME: Bug 1270790
+  iframe.setAttribute("remote", "true");
+  iframe.addEventListener("mozbrowserloadend", loadend);
+  iframe.src =
+    "data:text/html,<html>" +
+    '<body><img src="' +
+    imgSrc +
+    '" /></body></html>';
+
+  document.body.appendChild(iframe);
+
+  setTimeout(function() {
+    stopped = true;
+    iframe.stop();
+  }, 200);
+}
+
+function loadend() {
+  ok(stopped, "Iframes network connections were stopped");
+
+  // Wait 1 second and make sure there isn't a mozbrowsererror after stop();
+  iframe.addEventListener("mozbrowsererror", handleError);
+  window.setTimeout(function() {
+    iframe.removeEventListener("mozbrowsererror", handleError);
+    SimpleTest.finish();
+  }, 1000);
+}
+
+function handleError() {
+  ok(false, "mozbrowsererror should not be fired");
+}
+
+addEventListener("testready", runTest);
diff --git a/dom/browser-element/mochitest/browserElement_ThemeColor.js b/dom/browser-element/mochitest/browserElement_ThemeColor.js
new file mode 100644
index 000000000000..199efd0961d1
--- /dev/null
+++ b/dom/browser-element/mochitest/browserElement_ThemeColor.js
@@ -0,0 +1,88 @@
+/* Any copyright is dedicated to the public domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+// Test that the onmozbrowsermetachange event for theme-color works.
+"use strict";
+
+/* global browserElementTestHelpers */
+
+SimpleTest.waitForExplicitFinish();
+browserElementTestHelpers.setEnabledPref(true);
+browserElementTestHelpers.addPermission();
+
+function runTest() {
+  function loadFrameScript(script) {
+    SpecialPowers.getBrowserFrameMessageManager(iframe1).loadFrameScript(
+      "data:," + script,
+      /* allowDelayedLoad = */ false
+    );
+  }
+
+  let iframe1 = document.createElement("iframe");
+  iframe1.setAttribute("mozbrowser", "true");
+  iframe1.src =
+    "http://test/tests/dom/browser-element/mochitest/file_browserElement_ThemeColor.html";
+  iframe1.addEventListener("mozbrowsermetachange", tests);
+  document.body.appendChild(iframe1);
+
+  let numMetaChanges = 0;
+  function tests(e) {
+    let detail = e.detail;
+
+    switch (numMetaChanges++) {
+      case 0: {
+        is(detail.name, "theme-color", "name matches");
+        is(detail.content, "pink", "content matches");
+        is(detail.type, "added", "type matches");
+
+        let script =
+          "var meta = content.document.head.querySelector('meta');" +
+          "meta.content = 'green';";
+        loadFrameScript(script);
+        break;
+      }
+
+      case 1: {
+        is(detail.name, "theme-color", "name matches");
+        is(detail.content, "green", "content matches");
+        is(detail.type, "changed", "type matches");
+
+        let script =
+          "var meta = content.document.createElement('meta');" +
+          "meta.name = 'theme-group';" +
+          "meta.content = 'theme-productivity';" +
+          "content.document.head.appendChild(meta)";
+        loadFrameScript(script);
+        break;
+      }
+
+      case 2: {
+        is(detail.name, "theme-group", "name matches");
+        is(detail.content, "theme-productivity", "content matches");
+        is(detail.type, "added", "type matches");
+
+        let script =
+          "var meta = content.document.head.querySelector('meta');" +
+          "meta.parentNode.removeChild(meta);";
+        loadFrameScript(script);
+        break;
+      }
+
+      case 3: {
+        is(detail.name, "theme-color", "name matches");
+        is(detail.content, "green", "content matches");
+        is(detail.type, "removed", "type matches");
+
+        SimpleTest.finish();
+        break;
+      }
+
+      default: {
+        ok(false, "Too many metachange events.");
+        break;
+      }
+    }
+  }
+}
+
+window.addEventListener("testready", runTest);
diff --git a/dom/browser-element/mochitest/browserElement_Titlechange.js b/dom/browser-element/mochitest/browserElement_Titlechange.js
new file mode 100644
index 000000000000..7d5de9240da6
--- /dev/null
+++ b/dom/browser-element/mochitest/browserElement_Titlechange.js
@@ -0,0 +1,75 @@
+/* Any copyright is dedicated to the public domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+// Test that the onmozbrowsertitlechange event works.
+"use strict";
+
+/* global browserElementTestHelpers */
+
+SimpleTest.waitForExplicitFinish();
+browserElementTestHelpers.setEnabledPref(true);
+browserElementTestHelpers.addPermission();
+browserElementTestHelpers.allowTopLevelDataURINavigation();
+
+function runTest() {
+  var iframe1 = document.createElement("iframe");
+  iframe1.setAttribute("mozbrowser", "true");
+  document.body.appendChild(iframe1);
+
+  // iframe2 is a red herring; we modify its title but don't listen for
+  // titlechanges; we want to make sure that its titlechange events aren't
+  // picked up by the listener on iframe1.
+  var iframe2 = document.createElement("iframe");
+  iframe2.setAttribute("mozbrowser", "true");
+  document.body.appendChild(iframe2);
+
+  // iframe3 is another red herring.  It's not a mozbrowser, so we shouldn't
+  // get any titlechange events on it.
+  var iframe3 = document.createElement("iframe");
+  document.body.appendChild(iframe3);
+
+  var numTitleChanges = 0;
+
+  iframe1.addEventListener("mozbrowsertitlechange", function(e) {
+    // Ignore empty titles; these come from about:blank.
+    if (e.detail == "") {
+      return;
+    }
+
+    numTitleChanges++;
+
+    if (numTitleChanges == 1) {
+      is(e.detail, "Title");
+      SpecialPowers.getBrowserFrameMessageManager(iframe1).loadFrameScript(
+        "data:,content.document.title='New title';",
+        /* allowDelayedLoad = */ false
+      );
+      SpecialPowers.getBrowserFrameMessageManager(iframe2).loadFrameScript(
+        "data:,content.document.title='BAD TITLE 2';",
+        /* allowDelayedLoad = */ false
+      );
+    } else if (numTitleChanges == 2) {
+      is(e.detail, "New title");
+      iframe1.src =
+        "data:text/html,<html><head><title>Title 3</title></head><body></body></html>";
+    } else if (numTitleChanges == 3) {
+      is(e.detail, "Title 3");
+      SimpleTest.finish();
+    } else {
+      ok(false, "Too many titlechange events.");
+    }
+  });
+
+  iframe3.addEventListener("mozbrowsertitlechange", function(e) {
+    ok(false, "Should not get a titlechange event for iframe3.");
+  });
+
+  iframe1.src =
+    "data:text/html,<html><head><title>Title</title></head><body></body></html>";
+  iframe2.src =
+    "data:text/html,<html><head><title>BAD TITLE</title></head><body></body></html>";
+  iframe3.src =
+    "data:text/html,<html><head><title>SHOULD NOT GET EVENT</title></head><body></body></html>";
+}
+
+addEventListener("testready", runTest);
diff --git a/dom/browser-element/mochitest/browserElement_TopBarrier.js b/dom/browser-element/mochitest/browserElement_TopBarrier.js
new file mode 100644
index 000000000000..eae69c98b7da
--- /dev/null
+++ b/dom/browser-element/mochitest/browserElement_TopBarrier.js
@@ -0,0 +1,87 @@
+/* Any copyright is dedicated to the public domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+// Test that an <iframe mozbrowser> is a window.{top,parent,frameElement} barrier.
+"use strict";
+
+/* global browserElementTestHelpers */
+
+SimpleTest.waitForExplicitFinish();
+browserElementTestHelpers.setEnabledPref(true);
+browserElementTestHelpers.addPermission();
+browserElementTestHelpers.allowTopLevelDataURINavigation();
+
+var iframe;
+function runTest() {
+  iframe = document.createElement("iframe");
+  iframe.addEventListener("mozbrowserloadend", function() {
+    try {
+      outerIframeLoaded();
+    } catch (e) {
+      dump("Got error: " + e + "\n");
+    }
+  });
+  iframe.setAttribute("mozbrowser", "true");
+  iframe.src =
+    'data:text/html,Outer iframe <iframe id="inner-iframe"></iframe>';
+  // For kicks, this test uses a display:none iframe.  This shouldn't make a
+  // difference in anything.
+  iframe.style.display = "none";
+  document.body.appendChild(iframe);
+}
+
+var numMsgReceived = 0;
+function outerIframeLoaded() {
+  // If you're changing the amount of is() calls in injectedScript,
+  // also change the number in waitForMessages accordingly
+  var injectedScript =
+    "data:,function is(a, b, desc) {                                     \
+      if (a == b) {                                                      \
+        sendAsyncMessage('test:test-pass', desc);                        \
+      } else {                                                           \
+        sendAsyncMessage('test:test-fail', desc + ' ' + a + ' != ' + b); \
+      }                                                                  \
+    }                                                                    \
+    is(content.window.top, content.window, 'top');                       \
+    is(content.window.content, content.window, 'content');               \
+    is(content.window.parent, content.window, 'parent');                 \
+    is(content.window.frameElement, null, 'frameElement');               \
+    var innerIframe = content.document.getElementById('inner-iframe');   \
+    var innerWindow = innerIframe.contentWindow;                         \
+    is(innerWindow.top, content.window, 'inner top');                    \
+    is(innerWindow.content, content.window, 'inner content');            \
+    is(innerWindow.parent, content.window, 'inner parent');              \
+    is(innerWindow.frameElement, innerIframe, 'inner frameElement');";
+
+  var mm = SpecialPowers.getBrowserFrameMessageManager(iframe);
+
+  function onRecvTestPass(msg) {
+    numMsgReceived++;
+    ok(true, msg.json);
+  }
+  mm.addMessageListener("test:test-pass", onRecvTestPass);
+
+  function onRecvTestFail(msg) {
+    numMsgReceived++;
+    ok(false, msg.json);
+  }
+  mm.addMessageListener("test:test-fail", onRecvTestFail);
+
+  mm.loadFrameScript(injectedScript, /* allowDelayedLoad = */ false);
+
+  // 8 is the number of is() calls in injectedScript
+  waitForMessages(8);
+}
+
+function waitForMessages(num) {
+  if (numMsgReceived < num) {
+    SimpleTest.executeSoon(function() {
+      waitForMessages(num);
+    });
+    return;
+  }
+
+  SimpleTest.finish();
+}
+
+addEventListener("testready", runTest);
diff --git a/dom/browser-element/mochitest/browserElement_Viewmode.js b/dom/browser-element/mochitest/browserElement_Viewmode.js
new file mode 100644
index 000000000000..710d386b1779
--- /dev/null
+++ b/dom/browser-element/mochitest/browserElement_Viewmode.js
@@ -0,0 +1,74 @@
+/* Any copyright is dedicated to the public domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+// Test that the onmozbrowsermetachange event for viewmode works.
+"use strict";
+
+/* global browserElementTestHelpers */
+
+SimpleTest.waitForExplicitFinish();
+browserElementTestHelpers.setEnabledPref(true);
+browserElementTestHelpers.addPermission();
+
+function runTest() {
+  function loadFrameScript(script) {
+    SpecialPowers.getBrowserFrameMessageManager(iframe1).loadFrameScript(
+      "data:," + script,
+      /* allowDelayedLoad = */ false
+    );
+  }
+
+  let iframe1 = document.createElement("iframe");
+  iframe1.setAttribute("mozbrowser", "true");
+  iframe1.src =
+    "http://test/tests/dom/browser-element/mochitest/file_browserElement_Viewmode.html";
+  iframe1.addEventListener("mozbrowsermetachange", tests);
+  document.body.appendChild(iframe1);
+
+  let numMetaChanges = 0;
+  function tests(e) {
+    let detail = e.detail;
+
+    switch (numMetaChanges++) {
+      case 0: {
+        is(detail.name, "viewmode", "name matches");
+        is(detail.content, "projection=stereo", "content matches");
+        is(detail.type, "added", "type matches");
+
+        let script =
+          "var meta = content.document.head.querySelector('meta');" +
+          "meta.content = 'projection=mono';";
+        loadFrameScript(script);
+        break;
+      }
+
+      case 1: {
+        is(detail.name, "viewmode", "name matches");
+        is(detail.content, "projection=mono", "content matches");
+        is(detail.type, "changed", "type matches");
+
+        let script =
+          "var meta = content.document.head.querySelector('meta');" +
+          "meta.parentNode.removeChild(meta);";
+        loadFrameScript(script);
+        break;
+      }
+
+      case 2: {
+        is(detail.name, "viewmode", "name matches");
+        is(detail.content, "projection=mono", "content matches");
+        is(detail.type, "removed", "type matches");
+
+        SimpleTest.finish();
+        break;
+      }
+
+      default: {
+        ok(false, "Too many metachange events.");
+        break;
+      }
+    }
+  }
+}
+
+window.addEventListener("testready", runTest);
diff --git a/dom/browser-element/mochitest/browserElement_XFrameOptions.js b/dom/browser-element/mochitest/browserElement_XFrameOptions.js
new file mode 100644
index 000000000000..a1a85700297c
--- /dev/null
+++ b/dom/browser-element/mochitest/browserElement_XFrameOptions.js
@@ -0,0 +1,28 @@
+/* Any copyright is dedicated to the public domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+// Bug 770239 - Test that we can load pages with X-Frame-Options: Deny inside
+// <iframe mozbrowser>.
+"use strict";
+
+/* global browserElementTestHelpers */
+
+SimpleTest.waitForExplicitFinish();
+browserElementTestHelpers.setEnabledPref(true);
+browserElementTestHelpers.addPermission();
+
+function runTest() {
+  var iframe = document.createElement("iframe");
+  iframe.setAttribute("mozbrowser", "true");
+
+  // The page we load will fire an alert when it successfully loads.
+  iframe.addEventListener("mozbrowsershowmodalprompt", function(e) {
+    ok(true, "Got alert");
+    SimpleTest.finish();
+  });
+
+  document.body.appendChild(iframe);
+  iframe.src = "file_browserElement_XFrameOptions.sjs?DENY";
+}
+
+addEventListener("testready", runTest);
diff --git a/dom/browser-element/mochitest/browserElement_XFrameOptionsDeny.js b/dom/browser-element/mochitest/browserElement_XFrameOptionsDeny.js
new file mode 100644
index 000000000000..3973930db6db
--- /dev/null
+++ b/dom/browser-element/mochitest/browserElement_XFrameOptionsDeny.js
@@ -0,0 +1,69 @@
+/* Any copyright is dedicated to the public domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+// Bug 770239 - Test that X-Frame-Options will correctly block a page inside a
+// subframe of <iframe mozbrowser>.
+"use strict";
+
+/* global browserElementTestHelpers */
+
+SimpleTest.waitForExplicitFinish();
+browserElementTestHelpers.setEnabledPref(true);
+browserElementTestHelpers.addPermission();
+
+var initialScreenshotArrayBuffer;
+
+function arrayBuffersEqual(a, b) {
+  var x = new Int8Array(a);
+  var y = new Int8Array(b);
+  if (x.length != y.length) {
+    return false;
+  }
+
+  for (var i = 0; i < x.length; i++) {
+    if (x[i] != y[i]) {
+      return false;
+    }
+  }
+
+  return true;
+}
+
+function runTest() {
+  var iframe = document.createElement("iframe");
+  iframe.setAttribute("mozbrowser", "true");
+
+  // Our child will create two iframes, so make sure this iframe is big enough
+  // to show both of them without scrolling, so taking a screenshot gets both
+  // frames.
+  iframe.height = "1000px";
+
+  var step1, stepfinish;
+  iframe.addEventListener("mozbrowsershowmodalprompt", async function(e) {
+    switch (e.detail.message) {
+      case "step 1":
+        step1 = await SpecialPowers.snapshotWindow(iframe.contentWindow);
+        break;
+      case "step 2":
+        // The page has now attempted to load the X-Frame-Options page; take
+        // another screenshot.
+        stepfinish = await SpecialPowers.snapshotWindow(iframe.contentWindow);
+        ok(
+          step1.toDataURL() == stepfinish.toDataURL(),
+          "Screenshots should be identical"
+        );
+        SimpleTest.finish();
+        break;
+    }
+  });
+
+  document.body.appendChild(iframe);
+
+  // Load this page from a different origin than ourselves.  This page will, in
+  // turn, load a child from mochi.test:8888, our origin, with X-Frame-Options:
+  // SAMEORIGIN.  That load should be denied.
+  iframe.src =
+    "http://example.com/tests/dom/browser-element/mochitest/file_browserElement_XFrameOptionsDeny.html";
+}
+
+addEventListener("testready", runTest);
diff --git a/dom/browser-element/mochitest/browserElement_XFrameOptionsSameOrigin.js b/dom/browser-element/mochitest/browserElement_XFrameOptionsSameOrigin.js
new file mode 100644
index 000000000000..14e6e269d0a1
--- /dev/null
+++ b/dom/browser-element/mochitest/browserElement_XFrameOptionsSameOrigin.js
@@ -0,0 +1,31 @@
+/* Any copyright is dedicated to the public domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+// Bug 770239 - Load an X-Frame-Options: SAMEORIGIN page inside an <iframe>
+// inside <iframe mozbrowser>.  The two iframes will have the same origin, but
+// this page will be of a different origin.  The load should succeed.
+
+"use strict";
+
+/* global browserElementTestHelpers */
+
+SimpleTest.waitForExplicitFinish();
+browserElementTestHelpers.setEnabledPref(true);
+browserElementTestHelpers.addPermission();
+
+function runTest() {
+  var iframe = document.createElement("iframe");
+  iframe.setAttribute("mozbrowser", "true");
+
+  // The innermost page we load will fire an alert when it successfully loads.
+  iframe.addEventListener("mozbrowsershowmodalprompt", function(e) {
+    ok(true, "Got alert");
+    SimpleTest.finish();
+  });
+
+  document.body.appendChild(iframe);
+  iframe.src =
+    "http://example.com/tests/dom/browser-element/mochitest/file_browserElement_XFrameOptionsSameOrigin.html";
+}
+
+addEventListener("testready", runTest);
diff --git a/dom/browser-element/mochitest/chrome.ini b/dom/browser-element/mochitest/chrome.ini
new file mode 100644
index 000000000000..166c26435754
--- /dev/null
+++ b/dom/browser-element/mochitest/chrome.ini
@@ -0,0 +1,24 @@
+[DEFAULT]
+skip-if = e10s
+
+support-files =
+  audio.ogg
+  async.js
+  browserElementTestHelpers.js
+  browserElement_BackForward.js
+  browserElement_DocumentFirstPaint.js
+  browserElement_ReloadPostRequest.js
+  browserElement_SendEvent.js
+  browserElement_Stop.js
+  file_browserElement_SendEvent.html
+  file_bug709759.sjs
+  file_empty.html
+  file_post_request.html
+
+[test_browserElement_inproc_BackForward.html]
+[test_browserElement_inproc_DocumentFirstPaint.html]
+[test_browserElement_inproc_ReloadPostRequest.html]
+disabled = no modal prompt on POST reload for chrome window
+[test_browserElement_inproc_SendEvent.html]
+[test_browserElement_inproc_Stop.html]
+skip-if = (os == "win" && !debug) #Bug 1345410
diff --git a/dom/browser-element/mochitest/createNewTest.py b/dom/browser-element/mochitest/createNewTest.py
new file mode 100644
index 000000000000..801964b84f01
--- /dev/null
+++ b/dom/browser-element/mochitest/createNewTest.py
@@ -0,0 +1,126 @@
+"""A script to generate the browser-element test boilerplate.
+
+This script requires Python 2.7."""
+
+from __future__ import print_function
+
+import sys
+import os
+import stat
+import argparse
+import textwrap
+import subprocess
+
+html_template = textwrap.dedent("""\
+    <!DOCTYPE HTML>
+    <html>
+    <head>
+      <title>Test for Bug {bug}</title>
+      <script type="application/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
+      <script type="application/javascript" src="browserElementTestHelpers.js"></script>
+      <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+    </head>
+    <body>
+    <script type="application/javascript" src="browserElement_{test}.js">
+    </script>
+    </body>
+    </html>""")
+
+# Note: Curly braces are escaped as "{{".
+js_template = textwrap.dedent("""\
+    /* Any copyright is dedicated to the public domain.
+       http://creativecommons.org/publicdomain/zero/1.0/ */
+
+    // Bug {bug} - FILL IN TEST DESCRIPTION
+    "use strict";
+
+    SimpleTest.waitForExplicitFinish();
+    browserElementTestHelpers.setEnabledPref(true);
+    browserElementTestHelpers.addPermission();
+
+    function runTest() {{
+      var iframe = document.createElement('iframe');
+      iframe.setAttribute('mozbrowser', 'true');
+
+      // FILL IN TEST
+
+      document.body.appendChild(iframe);
+    }}
+
+    addEventListener('testready', runTest);
+    """)
+
+def print_fill(s):
+    print(textwrap.fill(textwrap.dedent(s)))
+
+def add_to_ini(filename, test, support_file=None):
+    """Add test to mochitest config {filename}, then open
+    $EDITOR and let the user move the filenames to their appropriate
+    places in the file.
+
+    """
+    lines_to_write = ['[{0}]'.format(test)]
+    if support_file:
+        lines_to_write += ['support-files = {0}'.format(support_file)]
+    lines_to_write += ['']
+    with open(filename, 'a') as f:
+        f.write('\n'.join(lines_to_write))
+
+    if 'EDITOR' not in os.environ or not os.environ['EDITOR']:
+        print_fill("""\
+            Now open {filename} and move the filenames to their correct places.")
+            (Define $EDITOR and I'll open your editor for you next time.)""".format(filename=filename))
+        return
+
+    # Count the number of lines in the file
+    with open(filename, 'r') as f:
+        num_lines = len(f.readlines())
+
+    try:
+        subprocess.call([os.environ['EDITOR'],
+                         '+%d' % (num_lines - len(lines_to_write) + 2),
+                         filename])
+    except Exception as e:
+        print_fill("Error opening $EDITOR: {0}.".format(e))
+        print()
+        print_fill("""\
+            Please open {filename} and move the filenames at the bottom of the
+            file to their correct places.""".format(filename=filename))
+
+def main(test_name, bug_number):
+    global html_template, js_template
+
+    def format(str):
+        return str.format(bug=bug_number, test=test_name)
+
+    def create_file(filename, template):
+        path = os.path.join(os.path.dirname(sys.argv[0]), format(filename))
+        # Create a new file, bailing with an error if the file exists.
+        fd = os.open(path, os.O_WRONLY | os.O_CREAT | os.O_EXCL)
+
+        try:
+            # This file has 777 permission when created, for whatever reason.  Make it rw-rw-r---.
+            os.fchmod(fd, stat.S_IRUSR | stat.S_IWUSR | stat.S_IRGRP | stat.S_IWGRP | stat.S_IROTH)
+        except:
+            # fchmod doesn't work on Windows.
+            pass
+
+        with os.fdopen(fd, 'w') as file:
+            file.write(format(template))
+
+    create_file('browserElement_{test}.js', js_template)
+    create_file('test_browserElement_inproc_{test}.html', html_template)
+    create_file('test_browserElement_oop_{test}.html', html_template)
+
+    add_to_ini('mochitest.ini',
+               format('test_browserElement_inproc_{test}.html'),
+               format('browserElement_{test}.js'))
+    add_to_ini('mochitest-oop.ini',
+               format('test_browserElement_oop_{test}.html'))
+
+if __name__ == '__main__':
+    parser = argparse.ArgumentParser(description="Create a new browser-element testcase.")
+    parser.add_argument('test_name')
+    parser.add_argument('bug_number', type=int)
+    args = parser.parse_args()
+    main(args.test_name, args.bug_number)
diff --git a/dom/browser-element/mochitest/file_browserElement_AlertInFrame.html b/dom/browser-element/mochitest/file_browserElement_AlertInFrame.html
new file mode 100644
index 000000000000..8bdac1d25d68
--- /dev/null
+++ b/dom/browser-element/mochitest/file_browserElement_AlertInFrame.html
@@ -0,0 +1,6 @@
+<html>
+<body>
+I'm file_browserElement_AlertInFrame.html.
+<iframe src='file_browserElement_AlertInFrame_Inner.html'></iframe>
+<body>
+</html>
diff --git a/dom/browser-element/mochitest/file_browserElement_AlertInFrame_Inner.html b/dom/browser-element/mochitest/file_browserElement_AlertInFrame_Inner.html
new file mode 100644
index 000000000000..9341eda00ff9
--- /dev/null
+++ b/dom/browser-element/mochitest/file_browserElement_AlertInFrame_Inner.html
@@ -0,0 +1,12 @@
+<html>
+<body>
+I'm file_browserElement_AlertInFrame_Inner.html.
+
+<script>
+addEventListener("load", function() {
+  alert("Hello");
+});
+</script>
+
+</body>
+</html>
diff --git a/dom/browser-element/mochitest/file_browserElement_CookiesNotThirdParty.html b/dom/browser-element/mochitest/file_browserElement_CookiesNotThirdParty.html
new file mode 100644
index 000000000000..ff122f31a44f
--- /dev/null
+++ b/dom/browser-element/mochitest/file_browserElement_CookiesNotThirdParty.html
@@ -0,0 +1,23 @@
+<html>
+<body>
+file_browserElement_CookiesNotThirdParty.html
+
+<script type='text/javascript'>
+if (location.search != "?step=2") {
+  // Step 1: Set a cookie.
+  document.cookie = "file_browserElement_CookiesNotThirdParty";
+  alert("next");
+} else {
+  // Step 2: Read the cookie.
+  if (document.cookie == "file_browserElement_CookiesNotThirdParty") {
+    alert("success: got the correct cookie");
+  } else {
+    alert('failure: got unexpected cookie: "' + document.cookie + '"');
+  }
+
+  alert("finish");
+}
+</script>
+
+</body>
+</html>
diff --git a/dom/browser-element/mochitest/file_browserElement_ForwardName.html b/dom/browser-element/mochitest/file_browserElement_ForwardName.html
new file mode 100644
index 000000000000..cf7e07277cde
--- /dev/null
+++ b/dom/browser-element/mochitest/file_browserElement_ForwardName.html
@@ -0,0 +1,14 @@
+<html>
+<body>
+<script>
+
+if (window.name == "foo") {
+  alert("success:window.name == 'foo'");
+} else {
+  alert("failure:window.name == '" + window.name + "', expected 'foo'");
+}
+
+window.open("file_browserElement_ForwardName.html#finish", "foo");
+</script>
+</body>
+</html>
diff --git a/dom/browser-element/mochitest/file_browserElement_LoadEvents.html b/dom/browser-element/mochitest/file_browserElement_LoadEvents.html
new file mode 100644
index 000000000000..a2bf2d3e1080
--- /dev/null
+++ b/dom/browser-element/mochitest/file_browserElement_LoadEvents.html
@@ -0,0 +1,15 @@
+<html>
+<body style="background-color:green;">
+
+<!-- Tests rely on the fact that there's an element in here called 'url' and
+     that there's visible text on the page. -->
+
+Aloha!  My URL is <span id='url'></span>.
+
+<script>
+// eslint-disable-next-line no-unsanitized/property
+document.getElementById("url").innerHTML = window.location;
+</script>
+
+</body>
+</html>
diff --git a/dom/browser-element/mochitest/file_browserElement_Metachange.sjs b/dom/browser-element/mochitest/file_browserElement_Metachange.sjs
new file mode 100644
index 000000000000..c63a047f7d23
--- /dev/null
+++ b/dom/browser-element/mochitest/file_browserElement_Metachange.sjs
@@ -0,0 +1,7 @@
+function handleRequest(request, response)
+{
+  var p = request.queryString.split('|');
+  response.setHeader('Content-Language', p[0], false);
+  response.write('<html><head><meta name="application-name" content="sjs"' +
+                  (p.length > 1 ? (' lang="' + p[1] + '"') : '') + '></head><body></body></html>');
+}
diff --git a/dom/browser-element/mochitest/file_browserElement_PrivateBrowsing.html b/dom/browser-element/mochitest/file_browserElement_PrivateBrowsing.html
new file mode 100644
index 000000000000..99432e2f2c4f
--- /dev/null
+++ b/dom/browser-element/mochitest/file_browserElement_PrivateBrowsing.html
@@ -0,0 +1,15 @@
+<html>
+<body>
+<script>
+
+if (location.href.includes("clear=true")) {
+  localStorage.removeItem("foo");
+  alert("CLEAR");
+} else {
+  var initialValue = localStorage.getItem("foo") || "EMPTY";
+  localStorage.setItem("foo", "bar");
+  alert(initialValue);
+}
+</script>
+</body>
+</html>
diff --git a/dom/browser-element/mochitest/file_browserElement_SecurityChange.html b/dom/browser-element/mochitest/file_browserElement_SecurityChange.html
new file mode 100644
index 000000000000..050df0d3b88e
--- /dev/null
+++ b/dom/browser-element/mochitest/file_browserElement_SecurityChange.html
@@ -0,0 +1,17 @@
+<html>
+<head>
+
+<script>
+if (location.search === "?broken") {
+  // Load something non-https.
+  var s = document.createElement("script");
+  s.src = "http://example.com/dom/browser-element/mochitest/file_empty_script.js";
+  document.head.appendChild(s);
+}
+</script>
+</head>
+
+<body>
+file_browserElement_SecurityChange.html.
+</body>
+</html>
diff --git a/dom/browser-element/mochitest/file_browserElement_SendEvent.html b/dom/browser-element/mochitest/file_browserElement_SendEvent.html
new file mode 100644
index 000000000000..0f336c4010ad
--- /dev/null
+++ b/dom/browser-element/mochitest/file_browserElement_SendEvent.html
@@ -0,0 +1,11 @@
+<html><body>
+<button>sendMouseEvent</button>
+</body><script>
+function changeHash(e) {
+  document.location.hash = e.type;
+}
+window.addEventListener("mousedown", changeHash);
+window.addEventListener("mousemove", changeHash);
+window.addEventListener("mouseup", changeHash);
+window.addEventListener("click", changeHash, true);
+</script></html>
diff --git a/dom/browser-element/mochitest/file_browserElement_SetInputMethodActive.html b/dom/browser-element/mochitest/file_browserElement_SetInputMethodActive.html
new file mode 100644
index 000000000000..5eb17e5f109f
--- /dev/null
+++ b/dom/browser-element/mochitest/file_browserElement_SetInputMethodActive.html
@@ -0,0 +1,2 @@
+<input autofocus value="hello" />
+<p>This is targetted mozbrowser frame.</p>
diff --git a/dom/browser-element/mochitest/file_browserElement_SetVisibleFrames_Inner.html b/dom/browser-element/mochitest/file_browserElement_SetVisibleFrames_Inner.html
new file mode 100644
index 000000000000..d1cdf04fad70
--- /dev/null
+++ b/dom/browser-element/mochitest/file_browserElement_SetVisibleFrames_Inner.html
@@ -0,0 +1,18 @@
+<html>
+<body>
+<script>
+
+var name = location.search.substring(1);
+addEventListener("load", function() {
+  setTimeout(function() {
+    alert(name + ":ready");
+  }, 0);
+});
+
+addEventListener("visibilitychange", function() {
+  alert(name + ":" + (document.hidden ? "hidden" : "visible"));
+});
+
+</script>
+</body>
+</html>
diff --git a/dom/browser-element/mochitest/file_browserElement_ThemeColor.html b/dom/browser-element/mochitest/file_browserElement_ThemeColor.html
new file mode 100644
index 000000000000..f8fb9f116d06
--- /dev/null
+++ b/dom/browser-element/mochitest/file_browserElement_ThemeColor.html
@@ -0,0 +1,8 @@
+<html>
+  <head>
+    <meta name="theme-color" content="pink">
+  </head>
+
+  <body>
+  </body>
+</html>
diff --git a/dom/browser-element/mochitest/file_browserElement_Viewmode.html b/dom/browser-element/mochitest/file_browserElement_Viewmode.html
new file mode 100644
index 000000000000..422279e0ae28
--- /dev/null
+++ b/dom/browser-element/mochitest/file_browserElement_Viewmode.html
@@ -0,0 +1,8 @@
+<html>
+  <head>
+    <meta name="viewmode" content="projection=stereo">
+  </head>
+
+  <body>
+  </body>
+</html>
diff --git a/dom/browser-element/mochitest/file_browserElement_XFrameOptions.sjs b/dom/browser-element/mochitest/file_browserElement_XFrameOptions.sjs
new file mode 100644
index 000000000000..7e23756802ab
--- /dev/null
+++ b/dom/browser-element/mochitest/file_browserElement_XFrameOptions.sjs
@@ -0,0 +1,9 @@
+function handleRequest(request, response)
+{
+  response.setHeader("X-Frame-Options", request.queryString, false);
+  response.setHeader("Content-Type", "text/html", false);
+
+  // Tests rely on this page not being entirely blank, because they take
+  // screenshots to determine whether this page was loaded.
+  response.write("<html><body>XFrameOptions test<script>alert('finish')</script></body></html>");
+}
diff --git a/dom/browser-element/mochitest/file_browserElement_XFrameOptionsAllowFrom.html b/dom/browser-element/mochitest/file_browserElement_XFrameOptionsAllowFrom.html
new file mode 100644
index 000000000000..31920670d78c
--- /dev/null
+++ b/dom/browser-element/mochitest/file_browserElement_XFrameOptionsAllowFrom.html
@@ -0,0 +1,39 @@
+<html>
+<body>
+
+  <!-- Try to load in a frame a cross-origin page which sends:
+     "X-Frame-Options: Allow-From http://mochi.test:8888/",
+       and a cross-origin page which sends
+     "X-Frame-Options: Allow-From http://example.com/". -->
+
+<script>
+
+// Make sure these iframes aren't too tall; they both need to fit inside the
+// iframe this page is contained in, without scrolling, in order for the test's
+// screenshots to work properly.
+
+var frame_src = "http://example.com/tests/dom/browser-element/mochitest/file_browserElement_XFrameOptionsAllowFrom.sjs";
+
+var iframe1 = document.createElement("iframe");
+iframe1.height = "300px";
+var iframe2 = document.createElement("iframe");
+iframe2.height = "300px";
+document.body.appendChild(iframe1);
+
+iframe1.addEventListener("load", function() {
+  // This causes our embedder to take a screenshot (and blocks until the
+  // screenshot is completed).
+  iframe2.addEventListener("load", function() {
+    alert("finish");
+  }, {once: true});
+
+  document.body.appendChild(iframe2);
+  iframe2.src = frame_src;
+}, {once: true});
+
+
+iframe1.src = frame_src + "?iframe1";
+</script>
+
+</body>
+</html>
diff --git a/dom/browser-element/mochitest/file_browserElement_XFrameOptionsAllowFrom.sjs b/dom/browser-element/mochitest/file_browserElement_XFrameOptionsAllowFrom.sjs
new file mode 100644
index 000000000000..4a5dbaaced4a
--- /dev/null
+++ b/dom/browser-element/mochitest/file_browserElement_XFrameOptionsAllowFrom.sjs
@@ -0,0 +1,16 @@
+function handleRequest(request, response)
+{
+  var content = 'step 1';
+  if (request.queryString == "iframe1") {
+      response.setHeader("X-Frame-Options", "Allow-From http://mochi.test:8888/")
+      content = 'finish';
+  } else {
+      response.setHeader("X-Frame-Options", "Allow-From http://example.com")
+  }
+
+  response.setHeader("Content-Type", "text/html", false);
+
+  // Tests rely on this page not being entirely blank, because they take
+  // screenshots to determine whether this page was loaded.
+  response.write("<html><body>XFrameOptions test<script>alert('" + content + "')</script></body></html>");
+}
diff --git a/dom/browser-element/mochitest/file_browserElement_XFrameOptionsDeny.html b/dom/browser-element/mochitest/file_browserElement_XFrameOptionsDeny.html
new file mode 100644
index 000000000000..0f3c366f63c2
--- /dev/null
+++ b/dom/browser-element/mochitest/file_browserElement_XFrameOptionsDeny.html
@@ -0,0 +1,55 @@
+<html>
+<body>
+
+<!-- Try to load in a frame a page which sends "X-Frame-Options: DENY", and a
+     cross-origin page which sends "X-Frame-Options: SAMEORIGIN". -->
+
+<script>
+
+// Make sure these iframes aren't too tall; they both need to fit inside the
+// iframe this page is contained in, without scrolling, in order for the test's
+// screenshots to work properly.
+
+var iframe1 = document.createElement("iframe");
+iframe1.height = "300px";
+var iframe2 = document.createElement("iframe");
+iframe2.height = "300px";
+document.body.appendChild(iframe1);
+document.body.appendChild(iframe2);
+
+// This causes our embedder to take a screenshot (and blocks until the
+// screenshot is completed).
+alert("step 1");
+
+// Wait for both iframes to load.
+
+var iframe1Loaded = false;
+iframe1.addEventListener("load", function() {
+  iframe1Loaded = true;
+  waitForBothLoads();
+}, {once: true});
+
+var iframe2Loaded = false;
+iframe2.addEventListener("load", function() {
+  iframe2Loaded = true;
+  waitForBothLoads();
+}, {once: true});
+
+function waitForBothLoads() {
+  if (iframe1Loaded && iframe2Loaded) {
+    setTimeout(function() {
+      // This causes our embedder to take another screenshot.
+      alert("step 2");
+    }, 0);
+  }
+}
+
+iframe1.src = "file_browserElement_XFrameOptions.sjs?DENY";
+
+// Load iframe2 with the origin of our parent.  Since we have a different
+// origin and are inside <iframe mozbrowser>, this should not load.
+iframe2.src = "http://mochi.test:8888/tests/dom/browser-element/mochitest/file_browserElement_XFrameOptions.sjs?SAMEORIGIN";
+</script>
+
+</body>
+</html>
diff --git a/dom/browser-element/mochitest/file_browserElement_XFrameOptionsSameOrigin.html b/dom/browser-element/mochitest/file_browserElement_XFrameOptionsSameOrigin.html
new file mode 100644
index 000000000000..11e75f141748
--- /dev/null
+++ b/dom/browser-element/mochitest/file_browserElement_XFrameOptionsSameOrigin.html
@@ -0,0 +1,5 @@
+<html>
+<body>
+<iframe src='file_browserElement_XFrameOptions.sjs?SAMEORIGIN'></iframe>
+</body>
+</html>
diff --git a/dom/browser-element/mochitest/file_bug709759.sjs b/dom/browser-element/mochitest/file_bug709759.sjs
new file mode 100644
index 000000000000..ce78b188b3a9
--- /dev/null
+++ b/dom/browser-element/mochitest/file_bug709759.sjs
@@ -0,0 +1,5 @@
+function handleRequest(request, response)
+{
+  response.processAsync();
+  response.setHeader("Content-Type", "image/jpeg", false);
+}
\ No newline at end of file
diff --git a/dom/browser-element/mochitest/file_bug741717.sjs b/dom/browser-element/mochitest/file_bug741717.sjs
new file mode 100644
index 000000000000..bde9ddfaed49
--- /dev/null
+++ b/dom/browser-element/mochitest/file_bug741717.sjs
@@ -0,0 +1,27 @@
+function handleRequest(request, response)
+{
+  function etag(count) {
+    return '"anetag' + count + '"';
+  }
+
+  var count = parseInt(getState('count'));
+  if (!count)
+    count = 0;
+
+  // reload(false) will make a request with If-None-Match headers
+  var ifNoneMatch = request.hasHeader("If-None-Match") ?
+    request.getHeader("If-None-Match") : "";
+
+  if (ifNoneMatch === etag(count)) {
+    response.setStatusLine(request.httpVersion, "304", "Not Modified");
+    return;
+  }
+
+  count++;
+  setState('count', count + '');
+
+  response.setHeader('Content-Type', 'text/html', false);
+  response.setHeader('Cache-Control', 'public, max-age=3600', false);
+  response.setHeader("ETag", etag(count), false);
+  response.write('<html><body>' + count + '</body></html>');
+}
diff --git a/dom/browser-element/mochitest/file_empty.html b/dom/browser-element/mochitest/file_empty.html
new file mode 100644
index 000000000000..b3a7ddd27c2b
--- /dev/null
+++ b/dom/browser-element/mochitest/file_empty.html
@@ -0,0 +1,15 @@
+<html>
+<body>
+
+<!-- Tests rely on the fact that there's an element in here called 'url' and
+     that there's visible text on the page. -->
+
+Aloha!  My URL is <span id='url'></span>.
+
+<script>
+// eslint-disable-next-line no-unsanitized/property
+document.getElementById("url").innerHTML = window.location;
+</script>
+
+</body>
+</html>
diff --git a/dom/browser-element/mochitest/file_empty_script.js b/dom/browser-element/mochitest/file_empty_script.js
new file mode 100644
index 000000000000..e69de29bb2d1
diff --git a/dom/browser-element/mochitest/file_focus.html b/dom/browser-element/mochitest/file_focus.html
new file mode 100644
index 000000000000..139904633002
--- /dev/null
+++ b/dom/browser-element/mochitest/file_focus.html
@@ -0,0 +1,24 @@
+<html>
+<body>
+
+Aloha!  My URL is <span id='url'></span>.
+<script>
+// eslint-disable-next-line no-unsanitized/property
+document.getElementById("url").innerHTML = window.location;
+</script>
+
+<script>
+  // The input element is getting synthesized key events and will prevent
+  // default on the first ESC keydown event.
+
+  var alreadyBlocked = false;
+
+  addEventListener("keydown", function(e) {
+    if (e.keyCode == KeyboardEvent.DOM_VK_ESCAPE && !alreadyBlocked) {
+      alreadyBlocked = true;
+      e.preventDefault();
+    }
+  });
+</script>
+</body>
+</html>
diff --git a/dom/browser-element/mochitest/file_http_401_response.sjs b/dom/browser-element/mochitest/file_http_401_response.sjs
new file mode 100644
index 000000000000..c40a252c3f04
--- /dev/null
+++ b/dom/browser-element/mochitest/file_http_401_response.sjs
@@ -0,0 +1,16 @@
+function handleRequest(request, response)
+{
+  var auth = "";
+  try {
+    auth = request.getHeader("Authorization");
+  } catch(e) {}
+
+  if (auth == "Basic aHR0cHVzZXI6aHR0cHBhc3M=") {
+    response.setStatusLine("1.1", 200, "OK");
+    response.write("<html><head><title>http auth success</title></head><html>");
+  } else {
+    response.setStatusLine("1.1", 401, "Http authentication required");
+    response.setHeader("WWW-Authenticate", "Basic realm=\"http_realm\"");
+    response.write("<html><head><title>http auth failed</title></head><html>");
+  }
+}
\ No newline at end of file
diff --git a/dom/browser-element/mochitest/file_http_407_response.sjs b/dom/browser-element/mochitest/file_http_407_response.sjs
new file mode 100644
index 000000000000..da2f27620d2e
--- /dev/null
+++ b/dom/browser-element/mochitest/file_http_407_response.sjs
@@ -0,0 +1,16 @@
+function handleRequest(request, response)
+{
+  var auth = "";
+  try {
+    auth = request.getHeader("Proxy-Authorization");
+  } catch(e) {}
+
+  if (auth == "Basic cHJveHl1c2VyOnByb3h5cGFzcw==") {
+    response.setStatusLine("1.1", 200, "OK");
+    response.write("<html><head><title>http auth success</title></head><html>");
+  } else {
+    response.setStatusLine("1.1", 407, "Proxy Authentication Required");
+    response.setHeader("Proxy-Authenticate", "Basic realm=\"http_realm\"");
+    response.write("<html><head><title>http auth failed</title></head><html>");
+  }
+}
diff --git a/dom/browser-element/mochitest/file_post_request.html b/dom/browser-element/mochitest/file_post_request.html
new file mode 100644
index 000000000000..8be28c811e2d
--- /dev/null
+++ b/dom/browser-element/mochitest/file_post_request.html
@@ -0,0 +1,15 @@
+<html>
+<head>
+  <script>
+  addEventListener("load", function() {
+    document.getElementsByTagName("form")[0].submit();
+  });
+  </script>
+</head>
+<body>
+  <form action="file_empty.html" method="POST">
+    <input type="text" name="postvalue" value="I am a test string!!" />
+    <input type="submit" />
+  </form>
+</body>
+</html>
diff --git a/dom/browser-element/mochitest/mochitest-oop.ini b/dom/browser-element/mochitest/mochitest-oop.ini
new file mode 100644
index 000000000000..6ac6538b8745
--- /dev/null
+++ b/dom/browser-element/mochitest/mochitest-oop.ini
@@ -0,0 +1,55 @@
+[DEFAULT]
+# FIXME(bz, bug 1504026): now that we're not testing OpenMixedProcess,
+# can we reenable these tests on Android and e10s?
+skip-if = os == "android" || e10s
+
+[test_browserElement_oop_Viewmode.html]
+[test_browserElement_oop_ThemeColor.html]
+[test_browserElement_inproc_ErrorSecurity.html]
+[test_browserElement_oop_Alert.html]
+[test_browserElement_oop_AlertInFrame.html]
+[test_browserElement_oop_Auth.html]
+[test_browserElement_oop_BackForward.html]
+disabled = Disabling some OOP tests for WebIDL scope changes (bug 1310706 for re-enabling)
+[test_browserElement_oop_BrowserWindowResize.html]
+[test_browserElement_oop_Close.html]
+[test_browserElement_oop_CookiesNotThirdParty.html]
+[test_browserElement_oop_CopyPaste.html]
+[test_browserElement_oop_DataURI.html]
+[test_browserElement_oop_DocumentFirstPaint.html]
+disabled = Disabling some OOP tests for WebIDL scope changes (bug 1310706 for re-enabling)
+[test_browserElement_oop_ErrorSecurity.html]
+[test_browserElement_oop_FirstPaint.html]
+[test_browserElement_oop_ForwardName.html]
+[test_browserElement_oop_Iconchange.html]
+[test_browserElement_oop_LoadEvents.html]
+[test_browserElement_oop_Metachange.html]
+[test_browserElement_oop_NoAudioTrack.html]
+disabled = Disabling some OOP tests for WebIDL scope changes (bug 1310706 for re-enabling)
+[test_browserElement_oop_Opensearch.html]
+disabled = Disabling some OOP tests for WebIDL scope changes (bug 1310706 for re-enabling)
+[test_browserElement_oop_PrivateBrowsing.html]
+skip-if = true # Bug 1315042
+[test_browserElement_oop_PromptCheck.html]
+[test_browserElement_oop_PromptConfirm.html]
+[test_browserElement_oop_Reload.html]
+disabled = Disabling some OOP tests for WebIDL scope changes (bug 1310706 for re-enabling)
+[test_browserElement_oop_ReloadPostRequest.html]
+disabled = Disabling some OOP tests for WebIDL scope changes (bug 1310706 for re-enabling)
+[test_browserElement_oop_RemoveBrowserElement.html]
+[test_browserElement_oop_ScrollEvent.html]
+[test_browserElement_oop_SecurityChange.html]
+skip-if = toolkit == 'android' #TIMED_OUT, bug 766586
+[test_browserElement_oop_SendEvent.html]
+disabled = Disabling some OOP tests for WebIDL scope changes (bug 1310706 for re-enabling)
+[test_browserElement_oop_Stop.html]
+disabled = Disabling some OOP tests for WebIDL scope changes (bug 1310706 for re-enabling)
+[test_browserElement_oop_Titlechange.html]
+[test_browserElement_oop_TopBarrier.html]
+[test_browserElement_oop_XFrameOptions.html]
+[test_browserElement_oop_XFrameOptionsDeny.html]
+disabled = Disabling some OOP tests for WebIDL scope changes (bug 1310706 for re-enabling)
+[test_browserElement_oop_XFrameOptionsSameOrigin.html]
+[test_browserElement_oop_ContextmenuEvents.html]
+[test_browserElement_oop_ExposableURI.html]
+skip-if = !e10s # Bug 1391349
diff --git a/dom/browser-element/mochitest/mochitest.ini b/dom/browser-element/mochitest/mochitest.ini
new file mode 100644
index 000000000000..6e5588ec84b5
--- /dev/null
+++ b/dom/browser-element/mochitest/mochitest.ini
@@ -0,0 +1,100 @@
+[DEFAULT]
+skip-if = e10s
+support-files =
+  audio.ogg
+  ../../../dom/media/test/short-video.ogv
+  async.js
+  browserElementTestHelpers.js
+  browserElement_Alert.js
+  browserElement_AlertInFrame.js
+  browserElement_Auth.js
+  browserElement_Viewmode.js
+  browserElement_ThemeColor.js
+  browserElement_BrowserWindowResize.js
+  browserElement_Close.js
+  browserElement_ContextmenuEvents.js
+  browserElement_CookiesNotThirdParty.js
+  browserElement_CopyPaste.js
+  browserElement_DataURI.js
+  browserElement_DataURILoad.html
+  browserElement_DataURILoad.js
+  browserElement_ErrorSecurity.js
+  browserElement_ExposableURI.js
+  browserElement_FirstPaint.js
+  browserElement_ForwardName.js
+  browserElement_Iconchange.js
+  browserElement_LoadEvents.js
+  browserElement_Metachange.js
+  browserElement_Opensearch.js
+  browserElement_PrivateBrowsing.js
+  browserElement_PromptCheck.js
+  browserElement_PromptConfirm.js
+  browserElement_Reload.js
+  browserElement_RemoveBrowserElement.js
+  browserElement_ScrollEvent.js
+  browserElement_SecurityChange.js
+  browserElement_Titlechange.js
+  browserElement_TopBarrier.js
+  browserElement_XFrameOptions.js
+  browserElement_XFrameOptionsDeny.js
+  browserElement_XFrameOptionsSameOrigin.js
+  file_browserElement_AlertInFrame.html
+  file_browserElement_AlertInFrame_Inner.html
+  file_browserElement_Viewmode.html
+  file_browserElement_ThemeColor.html
+  file_browserElement_CookiesNotThirdParty.html
+  file_browserElement_ForwardName.html
+  file_browserElement_LoadEvents.html
+  file_browserElement_Metachange.sjs
+  file_browserElement_PrivateBrowsing.html
+  file_browserElement_SecurityChange.html
+  file_browserElement_XFrameOptions.sjs
+  file_browserElement_XFrameOptionsDeny.html
+  file_browserElement_XFrameOptionsSameOrigin.html
+  file_bug741717.sjs
+  file_empty.html
+  file_empty_script.js
+  file_focus.html
+  file_http_401_response.sjs
+  file_http_407_response.sjs
+  noaudio.webm
+
+# Note: browserElementTestHelpers.js looks at the test's filename to determine
+# whether the test should be OOP.  "_oop_" signals OOP, "_inproc_" signals in
+# process.  Default is OOP.
+[test_browserElement_NoAttr.html]
+[test_browserElement_NoPref.html]
+[test_browserElement_NoPermission.html]
+[test_browserElement_inproc_Alert.html]
+[test_browserElement_inproc_Viewmode.html]
+[test_browserElement_inproc_ThemeColor.html]
+[test_browserElement_inproc_AlertInFrame.html]
+[test_browserElement_inproc_Auth.html]
+disabled = No longer supported
+[test_browserElement_inproc_BrowserWindowResize.html]
+[test_browserElement_inproc_Close.html]
+[test_browserElement_inproc_ContextmenuEvents.html]
+[test_browserElement_inproc_CookiesNotThirdParty.html]
+[test_browserElement_inproc_CopyPaste.html]
+[test_browserElement_inproc_DataURI.html]
+[test_browserElement_inproc_ExposableURI.html]
+[test_browserElement_inproc_FirstPaint.html]
+[test_browserElement_inproc_ForwardName.html]
+[test_browserElement_inproc_Iconchange.html]
+[test_browserElement_inproc_LoadEvents.html]
+[test_browserElement_inproc_Metachange.html]
+[test_browserElement_inproc_Opensearch.html]
+[test_browserElement_inproc_PrivateBrowsing.html]
+[test_browserElement_inproc_PromptCheck.html]
+[test_browserElement_inproc_PromptConfirm.html]
+[test_browserElement_inproc_RemoveBrowserElement.html]
+[test_browserElement_inproc_ScrollEvent.html]
+[test_browserElement_inproc_SecurityChange.html]
+[test_browserElement_inproc_Titlechange.html]
+[test_browserElement_inproc_TopBarrier.html]
+[test_browserElement_inproc_XFrameOptions.html]
+[test_browserElement_inproc_XFrameOptionsDeny.html]
+[test_browserElement_inproc_XFrameOptionsSameOrigin.html]
+[test_browserElement_inproc_Reload.html]
+disabled = bug 774100
+[test_browserElement_inproc_dataBlock.html]
diff --git a/dom/browser-element/mochitest/noaudio.webm b/dom/browser-element/mochitest/noaudio.webm
new file mode 100644
index 000000000000..9207017fb60e
Binary files /dev/null and b/dom/browser-element/mochitest/noaudio.webm differ
diff --git a/dom/browser-element/mochitest/test_browserElement_NoAttr.html b/dom/browser-element/mochitest/test_browserElement_NoAttr.html
new file mode 100644
index 000000000000..135a0c180951
--- /dev/null
+++ b/dom/browser-element/mochitest/test_browserElement_NoAttr.html
@@ -0,0 +1,46 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=710231
+-->
+<head>
+  <title>Test for Bug 710231</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="browserElementTestHelpers.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=710231">Mozilla Bug 710231</a>
+
+<!--
+  Test that an iframe without the |mozbrowser| attribute does not emit
+  mozbrowserX events.
+-->
+
+<script type="application/javascript">
+"use strict";
+
+SimpleTest.waitForExplicitFinish();
+
+function runTest() {
+  var iframe = document.getElementById("iframe");
+  iframe.addEventListener("mozbrowserloadstart", function() {
+    ok(false, "Should not send mozbrowserloadstart event.");
+  });
+
+  iframe.addEventListener("load", function() {
+    ok(true, "Got iframe load event.");
+    SimpleTest.finish();
+  });
+
+  iframe.src = browserElementTestHelpers.emptyPage1;
+}
+
+addEventListener("load", function() { SimpleTest.executeSoon(runTest); });
+
+</script>
+
+<iframe id='iframe'></iframe>
+
+</body>
+</html>
diff --git a/dom/browser-element/mochitest/test_browserElement_NoPermission.html b/dom/browser-element/mochitest/test_browserElement_NoPermission.html
new file mode 100644
index 000000000000..e98669488b39
--- /dev/null
+++ b/dom/browser-element/mochitest/test_browserElement_NoPermission.html
@@ -0,0 +1,49 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=710231
+-->
+<head>
+  <title>Test for Bug 710231</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="browserElementTestHelpers.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=710231">Mozilla Bug 710231</a>
+
+<!--
+  Test that an iframe with the |mozbrowser| attribute does not emit
+  mozbrowserX events when this page does not have the "browser" permission.
+-->
+
+<script type="application/javascript">
+"use strict";
+
+SimpleTest.waitForExplicitFinish();
+
+function runTest() {
+  var iframe = document.createElement("iframe");
+  iframe.setAttribute("mozbrowser", "true");
+  document.body.appendChild(iframe);
+
+  iframe.addEventListener("mozbrowserloadstart", function() {
+    ok(false, "Should not send mozbrowserloadstart event.");
+  });
+
+  iframe.addEventListener("load", function() {
+    ok(true, "Got iframe load event.");
+    SimpleTest.finish();
+  });
+
+  iframe.src = browserElementTestHelpers.emptyPage1;
+}
+
+browserElementTestHelpers.setEnabledPref(true);
+SpecialPowers.removePermission("browser", document);
+addEventListener("testready", runTest);
+
+</script>
+
+</body>
+</html>
diff --git a/dom/browser-element/mochitest/test_browserElement_NoPref.html b/dom/browser-element/mochitest/test_browserElement_NoPref.html
new file mode 100644
index 000000000000..27bdfdd19a82
--- /dev/null
+++ b/dom/browser-element/mochitest/test_browserElement_NoPref.html
@@ -0,0 +1,48 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=710231
+-->
+<head>
+  <title>Test for Bug 710231</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="browserElementTestHelpers.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=710231">Mozilla Bug 710231</a>
+
+<!--
+  Test that an iframe with the |mozbrowser| attribute does not emit
+  mozbrowserX events when they're globally pref'ed off.
+-->
+
+<script type="application/javascript">
+"use strict";
+
+SimpleTest.waitForExplicitFinish();
+
+function runTest() {
+  var iframe = document.createElement("iframe");
+  iframe.setAttribute("mozbrowser", "true");
+  document.body.appendChild(iframe);
+
+  iframe.addEventListener("mozbrowserloadstart", function() {
+    ok(false, "Should not send mozbrowserloadstart event.");
+  });
+
+  iframe.addEventListener("load", function() {
+    ok(true, "Got iframe load event.");
+    SimpleTest.finish();
+  });
+
+  iframe.src = browserElementTestHelpers.emptyPage1;
+}
+
+browserElementTestHelpers.setEnabledPref(false);
+addEventListener("testready", runTest);
+
+</script>
+
+</body>
+</html>
diff --git a/dom/browser-element/mochitest/test_browserElement_inproc_Alert.html b/dom/browser-element/mochitest/test_browserElement_inproc_Alert.html
new file mode 100644
index 000000000000..5cb9cbd44a7d
--- /dev/null
+++ b/dom/browser-element/mochitest/test_browserElement_inproc_Alert.html
@@ -0,0 +1,18 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=741587
+-->
+<head>
+  <title>Test for Bug 741587</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="browserElementTestHelpers.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=741587">Mozilla Bug 741587</a>
+
+<script type="application/javascript" src="browserElement_Alert.js">
+</script>
+</body>
+</html>
diff --git a/dom/browser-element/mochitest/test_browserElement_inproc_AlertInFrame.html b/dom/browser-element/mochitest/test_browserElement_inproc_AlertInFrame.html
new file mode 100644
index 000000000000..4eb2464f3600
--- /dev/null
+++ b/dom/browser-element/mochitest/test_browserElement_inproc_AlertInFrame.html
@@ -0,0 +1,13 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test for iframe mozbrowser</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="browserElementTestHelpers.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<script type="application/javascript" src="browserElement_AlertInFrame.js">
+</script>
+</body>
+</html>
diff --git a/dom/browser-element/mochitest/test_browserElement_inproc_Auth.html b/dom/browser-element/mochitest/test_browserElement_inproc_Auth.html
new file mode 100644
index 000000000000..ca4c52ba6cf5
--- /dev/null
+++ b/dom/browser-element/mochitest/test_browserElement_inproc_Auth.html
@@ -0,0 +1,18 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=741587
+-->
+<head>
+  <title>Test for Bug 775464</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="browserElementTestHelpers.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=775464">Mozilla Bug 775464</a>
+
+<script type="application/javascript" src="browserElement_Auth.js">
+</script>
+</body>
+</html>
diff --git a/dom/browser-element/mochitest/test_browserElement_inproc_BackForward.html b/dom/browser-element/mochitest/test_browserElement_inproc_BackForward.html
new file mode 100644
index 000000000000..939a05a333c5
--- /dev/null
+++ b/dom/browser-element/mochitest/test_browserElement_inproc_BackForward.html
@@ -0,0 +1,13 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test of browser element.</title>
+  <script src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="browserElementTestHelpers.js"></script>
+  <link rel="stylesheet" type="text/css" href="chrome://mochikit/content/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<script type="application/javascript" src="browserElement_BackForward.js">
+</script>
+</body>
+</html>
diff --git a/dom/browser-element/mochitest/test_browserElement_inproc_BrowserWindowResize.html b/dom/browser-element/mochitest/test_browserElement_inproc_BrowserWindowResize.html
new file mode 100644
index 000000000000..656021724b6f
--- /dev/null
+++ b/dom/browser-element/mochitest/test_browserElement_inproc_BrowserWindowResize.html
@@ -0,0 +1,13 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test for Bug 891763</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="browserElementTestHelpers.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<script type="application/javascript" src="browserElement_BrowserWindowResize.js">
+</script>
+</body>
+</html>
\ No newline at end of file
diff --git a/dom/browser-element/mochitest/test_browserElement_inproc_Close.html b/dom/browser-element/mochitest/test_browserElement_inproc_Close.html
new file mode 100644
index 000000000000..67a920b5790e
--- /dev/null
+++ b/dom/browser-element/mochitest/test_browserElement_inproc_Close.html
@@ -0,0 +1,18 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=757182
+-->
+<head>
+  <title>Test for Bug 757182</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="browserElementTestHelpers.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=757182">Mozilla Bug 757182</a>
+
+<script type="application/javascript" src="browserElement_Close.js">
+</script>
+</body>
+</html>
diff --git a/dom/browser-element/mochitest/test_browserElement_inproc_ContextmenuEvents.html b/dom/browser-element/mochitest/test_browserElement_inproc_ContextmenuEvents.html
new file mode 100644
index 000000000000..1d385c40dfef
--- /dev/null
+++ b/dom/browser-element/mochitest/test_browserElement_inproc_ContextmenuEvents.html
@@ -0,0 +1,13 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test for Contextmenu Events</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="browserElementTestHelpers.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<script type="application/javascript" src="browserElement_ContextmenuEvents.js">
+</script>
+</body>
+</html>
diff --git a/dom/browser-element/mochitest/test_browserElement_inproc_CookiesNotThirdParty.html b/dom/browser-element/mochitest/test_browserElement_inproc_CookiesNotThirdParty.html
new file mode 100644
index 000000000000..279b5bf689db
--- /dev/null
+++ b/dom/browser-element/mochitest/test_browserElement_inproc_CookiesNotThirdParty.html
@@ -0,0 +1,13 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test for Bug 806127</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="browserElementTestHelpers.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<script type="application/javascript" src="browserElement_CookiesNotThirdParty.js">
+</script>
+</body>
+</html>
\ No newline at end of file
diff --git a/dom/browser-element/mochitest/test_browserElement_inproc_CopyPaste.html b/dom/browser-element/mochitest/test_browserElement_inproc_CopyPaste.html
new file mode 100644
index 000000000000..73422d83125b
--- /dev/null
+++ b/dom/browser-element/mochitest/test_browserElement_inproc_CopyPaste.html
@@ -0,0 +1,18 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=987040
+-->
+<head>
+  <title>Test for Bug 987040</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="browserElementTestHelpers.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=987040">Mozilla Bug 987040</a>
+
+<script type="application/javascript" src="browserElement_CopyPaste.js">
+</script>
+</body>
+</html>
diff --git a/dom/browser-element/mochitest/test_browserElement_inproc_DataURI.html b/dom/browser-element/mochitest/test_browserElement_inproc_DataURI.html
new file mode 100644
index 000000000000..f55475d7b854
--- /dev/null
+++ b/dom/browser-element/mochitest/test_browserElement_inproc_DataURI.html
@@ -0,0 +1,18 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=720157
+-->
+<head>
+  <title>Test for Bug 720157</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="browserElementTestHelpers.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=720157">Mozilla Bug 720157</a>
+
+<script type='application/javascript' src='browserElement_DataURI.js'></script>
+
+</body>
+</html>
diff --git a/dom/browser-element/mochitest/test_browserElement_inproc_DocumentFirstPaint.html b/dom/browser-element/mochitest/test_browserElement_inproc_DocumentFirstPaint.html
new file mode 100644
index 000000000000..414e51290d3d
--- /dev/null
+++ b/dom/browser-element/mochitest/test_browserElement_inproc_DocumentFirstPaint.html
@@ -0,0 +1,13 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test for Bug 829486</title>
+  <script src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="browserElementTestHelpers.js"></script>
+  <link rel="stylesheet" type="text/css" href="chrome://mochikit/content/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<script type="application/javascript" src="browserElement_DocumentFirstPaint.js">
+</script>
+</body>
+</html>
diff --git a/dom/browser-element/mochitest/test_browserElement_inproc_ErrorSecurity.html b/dom/browser-element/mochitest/test_browserElement_inproc_ErrorSecurity.html
new file mode 100644
index 000000000000..9c0cf993f401
--- /dev/null
+++ b/dom/browser-element/mochitest/test_browserElement_inproc_ErrorSecurity.html
@@ -0,0 +1,13 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test for mozbrowser</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="browserElementTestHelpers.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<script type="application/javascript" src="browserElement_ErrorSecurity.js">
+</script>
+</body>
+</html>
diff --git a/dom/browser-element/mochitest/test_browserElement_inproc_ExposableURI.html b/dom/browser-element/mochitest/test_browserElement_inproc_ExposableURI.html
new file mode 100644
index 000000000000..1a4a3647d58a
--- /dev/null
+++ b/dom/browser-element/mochitest/test_browserElement_inproc_ExposableURI.html
@@ -0,0 +1,19 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=795317
+-->
+<head>
+  <title>Test for Bug 795317</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="browserElementTestHelpers.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=795317">Mozilla Bug 795317</a>
+
+<script type="application/javascript" src="browserElement_ExposableURI.js"></script>
+
+</body>
+</html>
+
diff --git a/dom/browser-element/mochitest/test_browserElement_inproc_FirstPaint.html b/dom/browser-element/mochitest/test_browserElement_inproc_FirstPaint.html
new file mode 100644
index 000000000000..615b35aa64a6
--- /dev/null
+++ b/dom/browser-element/mochitest/test_browserElement_inproc_FirstPaint.html
@@ -0,0 +1,13 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test for Bug 787378</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="browserElementTestHelpers.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<script type="application/javascript" src="browserElement_FirstPaint.js">
+</script>
+</body>
+</html>
\ No newline at end of file
diff --git a/dom/browser-element/mochitest/test_browserElement_inproc_ForwardName.html b/dom/browser-element/mochitest/test_browserElement_inproc_ForwardName.html
new file mode 100644
index 000000000000..0859c55ebf27
--- /dev/null
+++ b/dom/browser-element/mochitest/test_browserElement_inproc_ForwardName.html
@@ -0,0 +1,13 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test for Bug 781320</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="browserElementTestHelpers.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<script type="application/javascript" src="browserElement_ForwardName.js">
+</script>
+</body>
+</html>
\ No newline at end of file
diff --git a/dom/browser-element/mochitest/test_browserElement_inproc_Iconchange.html b/dom/browser-element/mochitest/test_browserElement_inproc_Iconchange.html
new file mode 100644
index 000000000000..bb6efb2c6aa7
--- /dev/null
+++ b/dom/browser-element/mochitest/test_browserElement_inproc_Iconchange.html
@@ -0,0 +1,19 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=719461
+-->
+<head>
+  <title>Test for Bug 719461</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="browserElementTestHelpers.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=719461">Mozilla Bug 719461</a>
+
+<script type="application/javascript" src="browserElement_Iconchange.js">
+</script>
+
+</body>
+</html>
diff --git a/dom/browser-element/mochitest/test_browserElement_inproc_LoadEvents.html b/dom/browser-element/mochitest/test_browserElement_inproc_LoadEvents.html
new file mode 100644
index 000000000000..fe32337c16d8
--- /dev/null
+++ b/dom/browser-element/mochitest/test_browserElement_inproc_LoadEvents.html
@@ -0,0 +1,18 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=710231
+-->
+<head>
+  <title>Test for Bug 710231</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="browserElementTestHelpers.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=710231">Mozilla Bug 710231</a>
+
+<script type="application/javascript" src="browserElement_LoadEvents.js"></script>
+
+</body>
+</html>
diff --git a/dom/browser-element/mochitest/test_browserElement_inproc_Metachange.html b/dom/browser-element/mochitest/test_browserElement_inproc_Metachange.html
new file mode 100644
index 000000000000..803ef519bdc6
--- /dev/null
+++ b/dom/browser-element/mochitest/test_browserElement_inproc_Metachange.html
@@ -0,0 +1,19 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=962626
+-->
+<head>
+  <title>Test for Bug 962626</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="browserElementTestHelpers.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=962626">Mozilla Bug 962626</a>
+
+<script type="application/javascript" src="browserElement_Metachange.js">
+</script>
+
+</body>
+</html>
diff --git a/dom/browser-element/mochitest/test_browserElement_inproc_Opensearch.html b/dom/browser-element/mochitest/test_browserElement_inproc_Opensearch.html
new file mode 100644
index 000000000000..4f14b8c5d43a
--- /dev/null
+++ b/dom/browser-element/mochitest/test_browserElement_inproc_Opensearch.html
@@ -0,0 +1,19 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=883002
+-->
+<head>
+  <title>Test for Bug 883002</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="browserElementTestHelpers.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=883002">Mozilla Bug 883002</a>
+
+<script type="application/javascript" src="browserElement_Opensearch.js">
+</script>
+
+</body>
+</html>
diff --git a/dom/browser-element/mochitest/test_browserElement_inproc_PrivateBrowsing.html b/dom/browser-element/mochitest/test_browserElement_inproc_PrivateBrowsing.html
new file mode 100644
index 000000000000..ff4dc1ee317c
--- /dev/null
+++ b/dom/browser-element/mochitest/test_browserElement_inproc_PrivateBrowsing.html
@@ -0,0 +1,19 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=832700
+-->
+<head>
+  <title>Test for Bug 832700</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="browserElementTestHelpers.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=832700">Mozilla Bug 832700</a>
+
+<script type="application/javascript" src="browserElement_PrivateBrowsing.js">
+</script>
+
+</body>
+</html>
diff --git a/dom/browser-element/mochitest/test_browserElement_inproc_PromptCheck.html b/dom/browser-element/mochitest/test_browserElement_inproc_PromptCheck.html
new file mode 100644
index 000000000000..155a41e600b3
--- /dev/null
+++ b/dom/browser-element/mochitest/test_browserElement_inproc_PromptCheck.html
@@ -0,0 +1,18 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=741587
+-->
+<head>
+  <title>Test for Bug 741587</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="browserElementTestHelpers.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=741587">Mozilla Bug 741587</a>
+
+<script type="application/javascript" src="browserElement_PromptCheck.js">
+</script>
+</body>
+</html>
diff --git a/dom/browser-element/mochitest/test_browserElement_inproc_PromptConfirm.html b/dom/browser-element/mochitest/test_browserElement_inproc_PromptConfirm.html
new file mode 100644
index 000000000000..9b8286bae359
--- /dev/null
+++ b/dom/browser-element/mochitest/test_browserElement_inproc_PromptConfirm.html
@@ -0,0 +1,18 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=741587
+-->
+<head>
+  <title>Test for Bug 741587</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="browserElementTestHelpers.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=741587">Mozilla Bug 741587</a>
+
+<script type="application/javascript" src="browserElement_PromptConfirm.js">
+</script>
+</body>
+</html>
diff --git a/dom/browser-element/mochitest/test_browserElement_inproc_Reload.html b/dom/browser-element/mochitest/test_browserElement_inproc_Reload.html
new file mode 100644
index 000000000000..392089ee01cd
--- /dev/null
+++ b/dom/browser-element/mochitest/test_browserElement_inproc_Reload.html
@@ -0,0 +1,13 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test of browser element.</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="browserElementTestHelpers.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<script type="application/javascript" src="browserElement_Reload.js">
+</script>
+</body>
+</html>
diff --git a/dom/browser-element/mochitest/test_browserElement_inproc_ReloadPostRequest.html b/dom/browser-element/mochitest/test_browserElement_inproc_ReloadPostRequest.html
new file mode 100644
index 000000000000..67036e6ae75e
--- /dev/null
+++ b/dom/browser-element/mochitest/test_browserElement_inproc_ReloadPostRequest.html
@@ -0,0 +1,13 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test of browser element.</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="browserElementTestHelpers.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<script type="application/javascript" src="browserElement_ReloadPostRequest.js">
+</script>
+</body>
+</html>
diff --git a/dom/browser-element/mochitest/test_browserElement_inproc_RemoveBrowserElement.html b/dom/browser-element/mochitest/test_browserElement_inproc_RemoveBrowserElement.html
new file mode 100644
index 000000000000..7ba34868d322
--- /dev/null
+++ b/dom/browser-element/mochitest/test_browserElement_inproc_RemoveBrowserElement.html
@@ -0,0 +1,18 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=787517
+-->
+<head>
+  <title>Test for Bug 787517</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="browserElementTestHelpers.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=787517">Mozilla Bug 787517</a>
+
+<script type="application/javascript" src="browserElement_RemoveBrowserElement.js">
+</script>
+</body>
+</html>
diff --git a/dom/browser-element/mochitest/test_browserElement_inproc_ScrollEvent.html b/dom/browser-element/mochitest/test_browserElement_inproc_ScrollEvent.html
new file mode 100644
index 000000000000..857ef98616a8
--- /dev/null
+++ b/dom/browser-element/mochitest/test_browserElement_inproc_ScrollEvent.html
@@ -0,0 +1,18 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=770847
+-->
+<head>
+  <title>Test for Bug 770847</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="browserElementTestHelpers.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=770847">Mozilla Bug 770847</a>
+
+<script type="application/javascript" src="browserElement_ScrollEvent.js">
+</script>
+</body>
+</html>
diff --git a/dom/browser-element/mochitest/test_browserElement_inproc_SecurityChange.html b/dom/browser-element/mochitest/test_browserElement_inproc_SecurityChange.html
new file mode 100644
index 000000000000..df32cf8598a8
--- /dev/null
+++ b/dom/browser-element/mochitest/test_browserElement_inproc_SecurityChange.html
@@ -0,0 +1,13 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test of browser element.</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="browserElementTestHelpers.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<script type="application/javascript" src="browserElement_SecurityChange.js">
+</script>
+</body>
+</html>
diff --git a/dom/browser-element/mochitest/test_browserElement_inproc_SendEvent.html b/dom/browser-element/mochitest/test_browserElement_inproc_SendEvent.html
new file mode 100644
index 000000000000..8fadbcd848e7
--- /dev/null
+++ b/dom/browser-element/mochitest/test_browserElement_inproc_SendEvent.html
@@ -0,0 +1,18 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=774809
+-->
+<head>
+  <title>Test for Bug 774809</title>
+  <script src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="browserElementTestHelpers.js"></script>
+  <link rel="stylesheet" type="text/css" href="chrome://mochikit/content/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=774809">Mozilla Bug 774809</a>
+
+<script type="application/javascript" src="browserElement_SendEvent.js">
+</script>
+</body>
+</html>
diff --git a/dom/browser-element/mochitest/test_browserElement_inproc_Stop.html b/dom/browser-element/mochitest/test_browserElement_inproc_Stop.html
new file mode 100644
index 000000000000..125bd29b996a
--- /dev/null
+++ b/dom/browser-element/mochitest/test_browserElement_inproc_Stop.html
@@ -0,0 +1,13 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test of browser element.</title>
+  <script src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="browserElementTestHelpers.js"></script>
+  <link rel="stylesheet" type="text/css" href="chrome://mochikit/content/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<script type="application/javascript" src="browserElement_Stop.js">
+</script>
+</body>
+</html>
diff --git a/dom/browser-element/mochitest/test_browserElement_inproc_ThemeColor.html b/dom/browser-element/mochitest/test_browserElement_inproc_ThemeColor.html
new file mode 100644
index 000000000000..18fd1619b157
--- /dev/null
+++ b/dom/browser-element/mochitest/test_browserElement_inproc_ThemeColor.html
@@ -0,0 +1,19 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=1013913
+-->
+<head>
+  <title>Test for Bug 1013913</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="browserElementTestHelpers.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1013913">Mozilla Bug 1013913</a>
+
+<script type="application/javascript" src="browserElement_ThemeColor.js">
+</script>
+
+</body>
+</html>
diff --git a/dom/browser-element/mochitest/test_browserElement_inproc_Titlechange.html b/dom/browser-element/mochitest/test_browserElement_inproc_Titlechange.html
new file mode 100644
index 000000000000..bff4e5741610
--- /dev/null
+++ b/dom/browser-element/mochitest/test_browserElement_inproc_Titlechange.html
@@ -0,0 +1,19 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=720157
+-->
+<head>
+  <title>Test for Bug 720157</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="browserElementTestHelpers.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=720157">Mozilla Bug 720157</a>
+
+<script type="application/javascript" src='browserElement_Titlechange.js'>
+</script>
+
+</body>
+</html>
diff --git a/dom/browser-element/mochitest/test_browserElement_inproc_TopBarrier.html b/dom/browser-element/mochitest/test_browserElement_inproc_TopBarrier.html
new file mode 100644
index 000000000000..4ab8b30f952f
--- /dev/null
+++ b/dom/browser-element/mochitest/test_browserElement_inproc_TopBarrier.html
@@ -0,0 +1,21 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=725796
+-->
+<head>
+  <title>Test for Bug 725796</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="browserElementTestHelpers.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=725796">Mozilla Bug 725796</a>
+
+<script type="application/javascript" src="browserElement_TopBarrier.js">
+</script>
+
+</body>
+</html>
+
+
diff --git a/dom/browser-element/mochitest/test_browserElement_inproc_Viewmode.html b/dom/browser-element/mochitest/test_browserElement_inproc_Viewmode.html
new file mode 100644
index 000000000000..9e49738b4bb3
--- /dev/null
+++ b/dom/browser-element/mochitest/test_browserElement_inproc_Viewmode.html
@@ -0,0 +1,19 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=1162844
+-->
+<head>
+  <title>Test for Bug 1162844</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="browserElementTestHelpers.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1162844">Mozilla Bug 1162844</a>
+
+<script type="application/javascript" src="browserElement_Viewmode.js">
+</script>
+
+</body>
+</html>
diff --git a/dom/browser-element/mochitest/test_browserElement_inproc_XFrameOptions.html b/dom/browser-element/mochitest/test_browserElement_inproc_XFrameOptions.html
new file mode 100644
index 000000000000..5fab3b5a8b68
--- /dev/null
+++ b/dom/browser-element/mochitest/test_browserElement_inproc_XFrameOptions.html
@@ -0,0 +1,13 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test for Bug 770239</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="browserElementTestHelpers.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<script type="application/javascript" src="browserElement_XFrameOptions.js">
+</script>
+</body>
+</html>
\ No newline at end of file
diff --git a/dom/browser-element/mochitest/test_browserElement_inproc_XFrameOptionsDeny.html b/dom/browser-element/mochitest/test_browserElement_inproc_XFrameOptionsDeny.html
new file mode 100644
index 000000000000..68a81b01e6cd
--- /dev/null
+++ b/dom/browser-element/mochitest/test_browserElement_inproc_XFrameOptionsDeny.html
@@ -0,0 +1,13 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test for Bug 770239</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="browserElementTestHelpers.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<script type="application/javascript" src="browserElement_XFrameOptionsDeny.js">
+</script>
+</body>
+</html>
\ No newline at end of file
diff --git a/dom/browser-element/mochitest/test_browserElement_inproc_XFrameOptionsSameOrigin.html b/dom/browser-element/mochitest/test_browserElement_inproc_XFrameOptionsSameOrigin.html
new file mode 100644
index 000000000000..2513b07efa76
--- /dev/null
+++ b/dom/browser-element/mochitest/test_browserElement_inproc_XFrameOptionsSameOrigin.html
@@ -0,0 +1,13 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test for Bug 770239</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="browserElementTestHelpers.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<script type="application/javascript" src="browserElement_XFrameOptionsSameOrigin.js">
+</script>
+</body>
+</html>
\ No newline at end of file
diff --git a/dom/browser-element/mochitest/test_browserElement_inproc_dataBlock.html b/dom/browser-element/mochitest/test_browserElement_inproc_dataBlock.html
new file mode 100644
index 000000000000..0aff1932e14f
--- /dev/null
+++ b/dom/browser-element/mochitest/test_browserElement_inproc_dataBlock.html
@@ -0,0 +1,18 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=1399170
+-->
+<head>
+  <title>Test for Bug 1399170</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="browserElementTestHelpers.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1399170">Mozilla Bug 1399170</a>
+
+<script type="application/javascript" src="browserElement_DataURILoad.js">
+</script>
+</body>
+</html>
diff --git a/dom/browser-element/mochitest/test_browserElement_oop_Alert.html b/dom/browser-element/mochitest/test_browserElement_oop_Alert.html
new file mode 100644
index 000000000000..5cb9cbd44a7d
--- /dev/null
+++ b/dom/browser-element/mochitest/test_browserElement_oop_Alert.html
@@ -0,0 +1,18 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=741587
+-->
+<head>
+  <title>Test for Bug 741587</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="browserElementTestHelpers.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=741587">Mozilla Bug 741587</a>
+
+<script type="application/javascript" src="browserElement_Alert.js">
+</script>
+</body>
+</html>
diff --git a/dom/browser-element/mochitest/test_browserElement_oop_AlertInFrame.html b/dom/browser-element/mochitest/test_browserElement_oop_AlertInFrame.html
new file mode 100644
index 000000000000..4eb2464f3600
--- /dev/null
+++ b/dom/browser-element/mochitest/test_browserElement_oop_AlertInFrame.html
@@ -0,0 +1,13 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test for iframe mozbrowser</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="browserElementTestHelpers.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<script type="application/javascript" src="browserElement_AlertInFrame.js">
+</script>
+</body>
+</html>
diff --git a/dom/browser-element/mochitest/test_browserElement_oop_Auth.html b/dom/browser-element/mochitest/test_browserElement_oop_Auth.html
new file mode 100644
index 000000000000..ca4c52ba6cf5
--- /dev/null
+++ b/dom/browser-element/mochitest/test_browserElement_oop_Auth.html
@@ -0,0 +1,18 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=741587
+-->
+<head>
+  <title>Test for Bug 775464</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="browserElementTestHelpers.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=775464">Mozilla Bug 775464</a>
+
+<script type="application/javascript" src="browserElement_Auth.js">
+</script>
+</body>
+</html>
diff --git a/dom/browser-element/mochitest/test_browserElement_oop_BackForward.html b/dom/browser-element/mochitest/test_browserElement_oop_BackForward.html
new file mode 100644
index 000000000000..c59ad3dc639c
--- /dev/null
+++ b/dom/browser-element/mochitest/test_browserElement_oop_BackForward.html
@@ -0,0 +1,13 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test of browser element.</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="browserElementTestHelpers.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<script type="application/javascript" src="browserElement_BackForward.js">
+</script>
+</body>
+</html>
diff --git a/dom/browser-element/mochitest/test_browserElement_oop_BrowserWindowResize.html b/dom/browser-element/mochitest/test_browserElement_oop_BrowserWindowResize.html
new file mode 100644
index 000000000000..656021724b6f
--- /dev/null
+++ b/dom/browser-element/mochitest/test_browserElement_oop_BrowserWindowResize.html
@@ -0,0 +1,13 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test for Bug 891763</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="browserElementTestHelpers.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<script type="application/javascript" src="browserElement_BrowserWindowResize.js">
+</script>
+</body>
+</html>
\ No newline at end of file
diff --git a/dom/browser-element/mochitest/test_browserElement_oop_Close.html b/dom/browser-element/mochitest/test_browserElement_oop_Close.html
new file mode 100644
index 000000000000..67a920b5790e
--- /dev/null
+++ b/dom/browser-element/mochitest/test_browserElement_oop_Close.html
@@ -0,0 +1,18 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=757182
+-->
+<head>
+  <title>Test for Bug 757182</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="browserElementTestHelpers.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=757182">Mozilla Bug 757182</a>
+
+<script type="application/javascript" src="browserElement_Close.js">
+</script>
+</body>
+</html>
diff --git a/dom/browser-element/mochitest/test_browserElement_oop_ContextmenuEvents.html b/dom/browser-element/mochitest/test_browserElement_oop_ContextmenuEvents.html
new file mode 100644
index 000000000000..1d385c40dfef
--- /dev/null
+++ b/dom/browser-element/mochitest/test_browserElement_oop_ContextmenuEvents.html
@@ -0,0 +1,13 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test for Contextmenu Events</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="browserElementTestHelpers.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<script type="application/javascript" src="browserElement_ContextmenuEvents.js">
+</script>
+</body>
+</html>
diff --git a/dom/browser-element/mochitest/test_browserElement_oop_CookiesNotThirdParty.html b/dom/browser-element/mochitest/test_browserElement_oop_CookiesNotThirdParty.html
new file mode 100644
index 000000000000..279b5bf689db
--- /dev/null
+++ b/dom/browser-element/mochitest/test_browserElement_oop_CookiesNotThirdParty.html
@@ -0,0 +1,13 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test for Bug 806127</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="browserElementTestHelpers.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<script type="application/javascript" src="browserElement_CookiesNotThirdParty.js">
+</script>
+</body>
+</html>
\ No newline at end of file
diff --git a/dom/browser-element/mochitest/test_browserElement_oop_CopyPaste.html b/dom/browser-element/mochitest/test_browserElement_oop_CopyPaste.html
new file mode 100644
index 000000000000..73422d83125b
--- /dev/null
+++ b/dom/browser-element/mochitest/test_browserElement_oop_CopyPaste.html
@@ -0,0 +1,18 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=987040
+-->
+<head>
+  <title>Test for Bug 987040</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="browserElementTestHelpers.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=987040">Mozilla Bug 987040</a>
+
+<script type="application/javascript" src="browserElement_CopyPaste.js">
+</script>
+</body>
+</html>
diff --git a/dom/browser-element/mochitest/test_browserElement_oop_DataURI.html b/dom/browser-element/mochitest/test_browserElement_oop_DataURI.html
new file mode 100644
index 000000000000..f55475d7b854
--- /dev/null
+++ b/dom/browser-element/mochitest/test_browserElement_oop_DataURI.html
@@ -0,0 +1,18 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=720157
+-->
+<head>
+  <title>Test for Bug 720157</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="browserElementTestHelpers.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=720157">Mozilla Bug 720157</a>
+
+<script type='application/javascript' src='browserElement_DataURI.js'></script>
+
+</body>
+</html>
diff --git a/dom/browser-element/mochitest/test_browserElement_oop_DocumentFirstPaint.html b/dom/browser-element/mochitest/test_browserElement_oop_DocumentFirstPaint.html
new file mode 100644
index 000000000000..4fbd934f1f28
--- /dev/null
+++ b/dom/browser-element/mochitest/test_browserElement_oop_DocumentFirstPaint.html
@@ -0,0 +1,13 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test for Bug 829486</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="browserElementTestHelpers.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<script type="application/javascript" src="browserElement_DocumentFirstPaint.js">
+</script>
+</body>
+</html>
diff --git a/dom/browser-element/mochitest/test_browserElement_oop_ErrorSecurity.html b/dom/browser-element/mochitest/test_browserElement_oop_ErrorSecurity.html
new file mode 100644
index 000000000000..9c0cf993f401
--- /dev/null
+++ b/dom/browser-element/mochitest/test_browserElement_oop_ErrorSecurity.html
@@ -0,0 +1,13 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test for mozbrowser</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="browserElementTestHelpers.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<script type="application/javascript" src="browserElement_ErrorSecurity.js">
+</script>
+</body>
+</html>
diff --git a/dom/browser-element/mochitest/test_browserElement_oop_ExposableURI.html b/dom/browser-element/mochitest/test_browserElement_oop_ExposableURI.html
new file mode 100644
index 000000000000..1a4a3647d58a
--- /dev/null
+++ b/dom/browser-element/mochitest/test_browserElement_oop_ExposableURI.html
@@ -0,0 +1,19 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=795317
+-->
+<head>
+  <title>Test for Bug 795317</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="browserElementTestHelpers.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=795317">Mozilla Bug 795317</a>
+
+<script type="application/javascript" src="browserElement_ExposableURI.js"></script>
+
+</body>
+</html>
+
diff --git a/dom/browser-element/mochitest/test_browserElement_oop_FirstPaint.html b/dom/browser-element/mochitest/test_browserElement_oop_FirstPaint.html
new file mode 100644
index 000000000000..615b35aa64a6
--- /dev/null
+++ b/dom/browser-element/mochitest/test_browserElement_oop_FirstPaint.html
@@ -0,0 +1,13 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test for Bug 787378</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="browserElementTestHelpers.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<script type="application/javascript" src="browserElement_FirstPaint.js">
+</script>
+</body>
+</html>
\ No newline at end of file
diff --git a/dom/browser-element/mochitest/test_browserElement_oop_ForwardName.html b/dom/browser-element/mochitest/test_browserElement_oop_ForwardName.html
new file mode 100644
index 000000000000..0859c55ebf27
--- /dev/null
+++ b/dom/browser-element/mochitest/test_browserElement_oop_ForwardName.html
@@ -0,0 +1,13 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test for Bug 781320</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="browserElementTestHelpers.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<script type="application/javascript" src="browserElement_ForwardName.js">
+</script>
+</body>
+</html>
\ No newline at end of file
diff --git a/dom/browser-element/mochitest/test_browserElement_oop_Iconchange.html b/dom/browser-element/mochitest/test_browserElement_oop_Iconchange.html
new file mode 100644
index 000000000000..bb6efb2c6aa7
--- /dev/null
+++ b/dom/browser-element/mochitest/test_browserElement_oop_Iconchange.html
@@ -0,0 +1,19 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=719461
+-->
+<head>
+  <title>Test for Bug 719461</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="browserElementTestHelpers.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=719461">Mozilla Bug 719461</a>
+
+<script type="application/javascript" src="browserElement_Iconchange.js">
+</script>
+
+</body>
+</html>
diff --git a/dom/browser-element/mochitest/test_browserElement_oop_LoadEvents.html b/dom/browser-element/mochitest/test_browserElement_oop_LoadEvents.html
new file mode 100644
index 000000000000..22b410ac7dae
--- /dev/null
+++ b/dom/browser-element/mochitest/test_browserElement_oop_LoadEvents.html
@@ -0,0 +1,19 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=710231
+-->
+<head>
+  <title>Test for Bug 710231</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="browserElementTestHelpers.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=710231">Mozilla Bug 710231</a>
+
+<script type="application/javascript" src="browserElement_LoadEvents.js"></script>
+
+</body>
+</html>
+
diff --git a/dom/browser-element/mochitest/test_browserElement_oop_Metachange.html b/dom/browser-element/mochitest/test_browserElement_oop_Metachange.html
new file mode 100644
index 000000000000..803ef519bdc6
--- /dev/null
+++ b/dom/browser-element/mochitest/test_browserElement_oop_Metachange.html
@@ -0,0 +1,19 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=962626
+-->
+<head>
+  <title>Test for Bug 962626</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="browserElementTestHelpers.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=962626">Mozilla Bug 962626</a>
+
+<script type="application/javascript" src="browserElement_Metachange.js">
+</script>
+
+</body>
+</html>
diff --git a/dom/browser-element/mochitest/test_browserElement_oop_NoAudioTrack.html b/dom/browser-element/mochitest/test_browserElement_oop_NoAudioTrack.html
new file mode 100644
index 000000000000..41586a4c81b1
--- /dev/null
+++ b/dom/browser-element/mochitest/test_browserElement_oop_NoAudioTrack.html
@@ -0,0 +1,13 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Bug 1227051 - No audio track video shouldn't register the AudioChannelAgent</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="browserElementTestHelpers.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<script type="application/javascript" src="browserElement_NoAudioTrack.js">
+</script>
+</body>
+</html>
\ No newline at end of file
diff --git a/dom/browser-element/mochitest/test_browserElement_oop_Opensearch.html b/dom/browser-element/mochitest/test_browserElement_oop_Opensearch.html
new file mode 100644
index 000000000000..4f14b8c5d43a
--- /dev/null
+++ b/dom/browser-element/mochitest/test_browserElement_oop_Opensearch.html
@@ -0,0 +1,19 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=883002
+-->
+<head>
+  <title>Test for Bug 883002</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="browserElementTestHelpers.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=883002">Mozilla Bug 883002</a>
+
+<script type="application/javascript" src="browserElement_Opensearch.js">
+</script>
+
+</body>
+</html>
diff --git a/dom/browser-element/mochitest/test_browserElement_oop_PrivateBrowsing.html b/dom/browser-element/mochitest/test_browserElement_oop_PrivateBrowsing.html
new file mode 100644
index 000000000000..ff4dc1ee317c
--- /dev/null
+++ b/dom/browser-element/mochitest/test_browserElement_oop_PrivateBrowsing.html
@@ -0,0 +1,19 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=832700
+-->
+<head>
+  <title>Test for Bug 832700</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="browserElementTestHelpers.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=832700">Mozilla Bug 832700</a>
+
+<script type="application/javascript" src="browserElement_PrivateBrowsing.js">
+</script>
+
+</body>
+</html>
diff --git a/dom/browser-element/mochitest/test_browserElement_oop_PromptCheck.html b/dom/browser-element/mochitest/test_browserElement_oop_PromptCheck.html
new file mode 100644
index 000000000000..155a41e600b3
--- /dev/null
+++ b/dom/browser-element/mochitest/test_browserElement_oop_PromptCheck.html
@@ -0,0 +1,18 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=741587
+-->
+<head>
+  <title>Test for Bug 741587</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="browserElementTestHelpers.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=741587">Mozilla Bug 741587</a>
+
+<script type="application/javascript" src="browserElement_PromptCheck.js">
+</script>
+</body>
+</html>
diff --git a/dom/browser-element/mochitest/test_browserElement_oop_PromptConfirm.html b/dom/browser-element/mochitest/test_browserElement_oop_PromptConfirm.html
new file mode 100644
index 000000000000..9b8286bae359
--- /dev/null
+++ b/dom/browser-element/mochitest/test_browserElement_oop_PromptConfirm.html
@@ -0,0 +1,18 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=741587
+-->
+<head>
+  <title>Test for Bug 741587</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="browserElementTestHelpers.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=741587">Mozilla Bug 741587</a>
+
+<script type="application/javascript" src="browserElement_PromptConfirm.js">
+</script>
+</body>
+</html>
diff --git a/dom/browser-element/mochitest/test_browserElement_oop_Reload.html b/dom/browser-element/mochitest/test_browserElement_oop_Reload.html
new file mode 100644
index 000000000000..392089ee01cd
--- /dev/null
+++ b/dom/browser-element/mochitest/test_browserElement_oop_Reload.html
@@ -0,0 +1,13 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test of browser element.</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="browserElementTestHelpers.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<script type="application/javascript" src="browserElement_Reload.js">
+</script>
+</body>
+</html>
diff --git a/dom/browser-element/mochitest/test_browserElement_oop_ReloadPostRequest.html b/dom/browser-element/mochitest/test_browserElement_oop_ReloadPostRequest.html
new file mode 100644
index 000000000000..67036e6ae75e
--- /dev/null
+++ b/dom/browser-element/mochitest/test_browserElement_oop_ReloadPostRequest.html
@@ -0,0 +1,13 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test of browser element.</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="browserElementTestHelpers.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<script type="application/javascript" src="browserElement_ReloadPostRequest.js">
+</script>
+</body>
+</html>
diff --git a/dom/browser-element/mochitest/test_browserElement_oop_RemoveBrowserElement.html b/dom/browser-element/mochitest/test_browserElement_oop_RemoveBrowserElement.html
new file mode 100644
index 000000000000..7ba34868d322
--- /dev/null
+++ b/dom/browser-element/mochitest/test_browserElement_oop_RemoveBrowserElement.html
@@ -0,0 +1,18 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=787517
+-->
+<head>
+  <title>Test for Bug 787517</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="browserElementTestHelpers.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=787517">Mozilla Bug 787517</a>
+
+<script type="application/javascript" src="browserElement_RemoveBrowserElement.js">
+</script>
+</body>
+</html>
diff --git a/dom/browser-element/mochitest/test_browserElement_oop_ScrollEvent.html b/dom/browser-element/mochitest/test_browserElement_oop_ScrollEvent.html
new file mode 100644
index 000000000000..857ef98616a8
--- /dev/null
+++ b/dom/browser-element/mochitest/test_browserElement_oop_ScrollEvent.html
@@ -0,0 +1,18 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=770847
+-->
+<head>
+  <title>Test for Bug 770847</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="browserElementTestHelpers.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=770847">Mozilla Bug 770847</a>
+
+<script type="application/javascript" src="browserElement_ScrollEvent.js">
+</script>
+</body>
+</html>
diff --git a/dom/browser-element/mochitest/test_browserElement_oop_SecurityChange.html b/dom/browser-element/mochitest/test_browserElement_oop_SecurityChange.html
new file mode 100644
index 000000000000..df32cf8598a8
--- /dev/null
+++ b/dom/browser-element/mochitest/test_browserElement_oop_SecurityChange.html
@@ -0,0 +1,13 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test of browser element.</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="browserElementTestHelpers.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<script type="application/javascript" src="browserElement_SecurityChange.js">
+</script>
+</body>
+</html>
diff --git a/dom/browser-element/mochitest/test_browserElement_oop_SendEvent.html b/dom/browser-element/mochitest/test_browserElement_oop_SendEvent.html
new file mode 100644
index 000000000000..a81849f10907
--- /dev/null
+++ b/dom/browser-element/mochitest/test_browserElement_oop_SendEvent.html
@@ -0,0 +1,18 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=774809
+-->
+<head>
+  <title>Test for Bug 774809</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="browserElementTestHelpers.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=774809">Mozilla Bug 774809</a>
+
+<script type="application/javascript" src="browserElement_SendEvent.js">
+</script>
+</body>
+</html>
diff --git a/dom/browser-element/mochitest/test_browserElement_oop_Stop.html b/dom/browser-element/mochitest/test_browserElement_oop_Stop.html
new file mode 100644
index 000000000000..749c4f999653
--- /dev/null
+++ b/dom/browser-element/mochitest/test_browserElement_oop_Stop.html
@@ -0,0 +1,13 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test of browser element.</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="browserElementTestHelpers.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<script type="application/javascript" src="browserElement_Stop.js">
+</script>
+</body>
+</html>
diff --git a/dom/browser-element/mochitest/test_browserElement_oop_ThemeColor.html b/dom/browser-element/mochitest/test_browserElement_oop_ThemeColor.html
new file mode 100644
index 000000000000..18fd1619b157
--- /dev/null
+++ b/dom/browser-element/mochitest/test_browserElement_oop_ThemeColor.html
@@ -0,0 +1,19 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=1013913
+-->
+<head>
+  <title>Test for Bug 1013913</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="browserElementTestHelpers.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1013913">Mozilla Bug 1013913</a>
+
+<script type="application/javascript" src="browserElement_ThemeColor.js">
+</script>
+
+</body>
+</html>
diff --git a/dom/browser-element/mochitest/test_browserElement_oop_Titlechange.html b/dom/browser-element/mochitest/test_browserElement_oop_Titlechange.html
new file mode 100644
index 000000000000..bff4e5741610
--- /dev/null
+++ b/dom/browser-element/mochitest/test_browserElement_oop_Titlechange.html
@@ -0,0 +1,19 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=720157
+-->
+<head>
+  <title>Test for Bug 720157</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="browserElementTestHelpers.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=720157">Mozilla Bug 720157</a>
+
+<script type="application/javascript" src='browserElement_Titlechange.js'>
+</script>
+
+</body>
+</html>
diff --git a/dom/browser-element/mochitest/test_browserElement_oop_TopBarrier.html b/dom/browser-element/mochitest/test_browserElement_oop_TopBarrier.html
new file mode 100644
index 000000000000..0524af5c54a9
--- /dev/null
+++ b/dom/browser-element/mochitest/test_browserElement_oop_TopBarrier.html
@@ -0,0 +1,20 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=725796
+-->
+<head>
+  <title>Test for Bug 725796</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="browserElementTestHelpers.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=725796">Mozilla Bug 725796</a>
+
+<script type="application/javascript" src="browserElement_TopBarrier.js">
+</script>
+
+</body>
+</html>
+
diff --git a/dom/browser-element/mochitest/test_browserElement_oop_Viewmode.html b/dom/browser-element/mochitest/test_browserElement_oop_Viewmode.html
new file mode 100644
index 000000000000..9e49738b4bb3
--- /dev/null
+++ b/dom/browser-element/mochitest/test_browserElement_oop_Viewmode.html
@@ -0,0 +1,19 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=1162844
+-->
+<head>
+  <title>Test for Bug 1162844</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="browserElementTestHelpers.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1162844">Mozilla Bug 1162844</a>
+
+<script type="application/javascript" src="browserElement_Viewmode.js">
+</script>
+
+</body>
+</html>
diff --git a/dom/browser-element/mochitest/test_browserElement_oop_XFrameOptions.html b/dom/browser-element/mochitest/test_browserElement_oop_XFrameOptions.html
new file mode 100644
index 000000000000..5fab3b5a8b68
--- /dev/null
+++ b/dom/browser-element/mochitest/test_browserElement_oop_XFrameOptions.html
@@ -0,0 +1,13 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test for Bug 770239</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="browserElementTestHelpers.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<script type="application/javascript" src="browserElement_XFrameOptions.js">
+</script>
+</body>
+</html>
\ No newline at end of file
diff --git a/dom/browser-element/mochitest/test_browserElement_oop_XFrameOptionsDeny.html b/dom/browser-element/mochitest/test_browserElement_oop_XFrameOptionsDeny.html
new file mode 100644
index 000000000000..68a81b01e6cd
--- /dev/null
+++ b/dom/browser-element/mochitest/test_browserElement_oop_XFrameOptionsDeny.html
@@ -0,0 +1,13 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test for Bug 770239</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="browserElementTestHelpers.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<script type="application/javascript" src="browserElement_XFrameOptionsDeny.js">
+</script>
+</body>
+</html>
\ No newline at end of file
diff --git a/dom/browser-element/mochitest/test_browserElement_oop_XFrameOptionsSameOrigin.html b/dom/browser-element/mochitest/test_browserElement_oop_XFrameOptionsSameOrigin.html
new file mode 100644
index 000000000000..2513b07efa76
--- /dev/null
+++ b/dom/browser-element/mochitest/test_browserElement_oop_XFrameOptionsSameOrigin.html
@@ -0,0 +1,13 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test for Bug 770239</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="browserElementTestHelpers.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<script type="application/javascript" src="browserElement_XFrameOptionsSameOrigin.js">
+</script>
+</body>
+</html>
\ No newline at end of file
diff --git a/dom/browser-element/moz.build b/dom/browser-element/moz.build
index e1095697682e..3aeafe4b7a2e 100644
--- a/dom/browser-element/moz.build
+++ b/dom/browser-element/moz.build
@@ -35,3 +35,12 @@ LOCAL_INCLUDES += [
     '/dom/base',
     '/dom/ipc',
 ]
+
+MOCHITEST_MANIFESTS += [
+    'mochitest/mochitest-oop.ini',
+    'mochitest/mochitest.ini',
+]
+
+MOCHITEST_CHROME_MANIFESTS += [
+    'mochitest/chrome.ini',
+]
diff --git a/dom/chrome-webidl/MessageManager.webidl b/dom/chrome-webidl/MessageManager.webidl
index 54094490e7ea..f36bc4219dcc 100644
--- a/dom/chrome-webidl/MessageManager.webidl
+++ b/dom/chrome-webidl/MessageManager.webidl
@@ -195,6 +195,11 @@ dictionary ReceiveMessageArgument
 
   sequence<MessagePort> ports;
 
+  /**
+   * Principal for the window app.
+   */
+  required Principal? principal;
+
   FrameLoader targetFrameLoader;
 };
 
@@ -311,6 +316,7 @@ interface mixin MessageSenderMixin {
   void sendAsyncMessage(optional DOMString? messageName = null,
                         optional any obj,
                         optional object? objects = null,
+                        optional Principal? principal = null,
                         optional any transfers);
 
   /**
@@ -351,7 +357,8 @@ interface mixin SyncMessageSenderMixin
   [Throws]
   sequence<any> sendSyncMessage(optional DOMString? messageName = null,
                                 optional any obj,
-                                optional object? objects = null);
+                                optional object? objects = null,
+                                optional Principal? principal = null);
 
   /**
    * Like |sendSyncMessage()|, except re-entrant. New RPC messages may be
@@ -365,7 +372,8 @@ interface mixin SyncMessageSenderMixin
   [Throws]
   sequence<any> sendRpcMessage(optional DOMString? messageName = null,
                                optional any obj,
-                               optional object? objects = null);
+                               optional object? objects = null,
+                               optional Principal? principal = null);
 };
 
 /**
@@ -388,6 +396,13 @@ interface mixin MessageManagerGlobal
    */
   void dump(DOMString str);
 
+  /**
+   * If leak detection is enabled, print a note to the leak log that this
+   * process will intentionally crash.
+   */
+  [Throws]
+  void privateNoteIntentionalCrash();
+
   /**
    * Ascii base64 data to binary data and vice versa
    */
diff --git a/dom/crypto/test/file_indexedDB.html b/dom/crypto/test/file_indexedDB.html
index 435f623892a7..390b3f80dbf2 100644
--- a/dom/crypto/test/file_indexedDB.html
+++ b/dom/crypto/test/file_indexedDB.html
@@ -76,10 +76,7 @@
 
     openDatabase()
       .then(retrieveKey).then(generateKey).then(storeKey)
-      .then(() => parent.postMessage("ok", "*"))
-      .catch(error => {
-        parent.postMessage(String(error), "*");
-      });
+      .then(() => alert("ok")).catch(alert);
   </script>
 </body>
 </html>
diff --git a/dom/crypto/test/mochitest.ini b/dom/crypto/test/mochitest.ini
index 8b416cc906ed..febe769bb772 100644
--- a/dom/crypto/test/mochitest.ini
+++ b/dom/crypto/test/mochitest.ini
@@ -9,7 +9,6 @@ support-files =
   util.js
 
 [test_indexedDB.html]
-skip-if = !fission # Requires iframes to run in separate processes.
 [test_WebCrypto.html]
 [test_WebCrypto_DH.html]
 [test_WebCrypto_ECDH.html]
diff --git a/dom/crypto/test/test_indexedDB.html b/dom/crypto/test/test_indexedDB.html
index ba5a91c6d4b9..b68f0c51e83c 100644
--- a/dom/crypto/test/test_indexedDB.html
+++ b/dom/crypto/test/test_indexedDB.html
@@ -18,31 +18,42 @@
     const TEST_URI = "https://example.com/tests/" +
                      "dom/crypto/test/file_indexedDB.html";
 
-    function createFrame() {
+    SimpleTest.waitForExplicitFinish();
+
+    function createMozBrowserFrame(cb) {
       let frame = document.createElement("iframe");
+      SpecialPowers.wrap(frame).mozbrowser = true;
       frame.src = TEST_URI;
 
-      return new Promise(resolve => {
-        addEventListener("message", event => {
-          is(event.source.frameElement, frame,
-             "Message must come from the correct iframe");
-          resolve([frame, event.data]);
-        }, { once: true });
+      frame.addEventListener("mozbrowsershowmodalprompt", function(e) {
+        cb(frame, e.detail.message);
+      }, {once: true});
 
-        document.body.appendChild(frame);
+      document.body.appendChild(frame);
+    }
+
+    function runTest() {
+      // Load the test app once, to generate and store keys.
+      createMozBrowserFrame((frame, result) => {
+        is(result, "ok", "stored keys successfully");
+        frame.remove();
+
+        // Load the test app again to retrieve stored keys.
+        createMozBrowserFrame((recFrame, recResult) => {
+          is(recResult, "ok", "retrieved keys successfully");
+          recFrame.remove();
+          SimpleTest.finish();
+        });
       });
     }
 
-    add_task(async function() {
-      // Load the test app once, to generate and store keys.
-      let [frame, result] = await createFrame();
-      is(result, "ok", "stored keys successfully");
-      frame.remove();
-
-      // Load the test app again to retrieve stored keys.
-      let [recFrame, recResult] = await createFrame();
-      is(recResult, "ok", "retrieved keys successfully");
-      recFrame.remove();
+    addEventListener("load", function() {
+      SpecialPowers.addPermission("browser", true, document);
+      SpecialPowers.pushPrefEnv({set: [
+        ["dom.ipc.browser_frames.oop_by_default", true],
+        ["dom.mozBrowserFramesEnabled", true],
+        ["network.disable.ipc.security", true],
+      ]}, runTest);
     });
   </script>
 </body>
diff --git a/dom/file/tests/file_ipc_messagemanager_blob.html b/dom/file/tests/file_ipc_messagemanager_blob.html
new file mode 100644
index 000000000000..dbdd64a34b6b
--- /dev/null
+++ b/dom/file/tests/file_ipc_messagemanager_blob.html
@@ -0,0 +1 @@
+<!DOCTYPE HTML><html><body></body></html>
diff --git a/dom/file/tests/mochitest.ini b/dom/file/tests/mochitest.ini
index dd53385abb81..7449475e68f5 100644
--- a/dom/file/tests/mochitest.ini
+++ b/dom/file/tests/mochitest.ini
@@ -21,6 +21,8 @@ support-files =
 [test_blobconstructor.html]
 [test_blobURL_expiring.html]
 [test_file_from_blob.html]
+[test_ipc_messagemanager_blob.html]
+support-files = file_ipc_messagemanager_blob.html
 [test_nonascii_blob_url.html]
 [test_file_negative_date.html]
 [test_fileapi_basic.html]
diff --git a/dom/file/tests/test_ipc_messagemanager_blob.html b/dom/file/tests/test_ipc_messagemanager_blob.html
new file mode 100644
index 000000000000..29065d8d6639
--- /dev/null
+++ b/dom/file/tests/test_ipc_messagemanager_blob.html
@@ -0,0 +1,143 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test for OOP Blobs in MessageManager</title>
+  <script src="/tests/SimpleTest/SimpleTest.js">
+  </script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+  <script type="application/javascript">
+    "use strict";
+
+    SimpleTest.waitForExplicitFinish();
+
+    const childFrameURL = "file_ipc_messagemanager_blob.html";
+
+    function childFrameScript() {
+      "use strict";
+
+      Cu.importGlobalProperties(["Blob"]);
+
+      addMessageListener("test:ipcClonedMessage", function(message) {
+        if (!Blob.isInstance(message.json)) {
+          sendAsyncMessage(message.name, message.json);
+          return;
+        }
+
+        let reader = new FileReader();
+        reader.addEventListener("load", function() {
+          let response = reader.result == "this is a great success!" ?
+                         message.json :
+                         "error";
+          sendAsyncMessage(message.name, response);
+        });
+        reader.readAsText(message.json);
+      });
+    }
+
+    function runTests() {
+      function done() {
+        SpecialPowers.removePermission("browser", document);
+        SimpleTest.finish();
+      }
+
+      ok("Browser prefs set.");
+
+      let iframe = document.createElement("iframe");
+      SpecialPowers.wrap(iframe).mozbrowser = true;
+      iframe.id = "iframe";
+      iframe.src = childFrameURL;
+
+      iframe.addEventListener("mozbrowserloadend", function() {
+        ok(true, "Got iframe load event.");
+
+        const blobString = "this is a great success!";
+
+        const messages = [
+          "hi!",
+          "",
+          2,
+          -.04,
+          3432987324987239872948732982,
+          true,
+          false,
+          null,
+          0,
+
+          // Make sure this one is always last.
+          new Blob(["this ", "is ", "a ", "great ", "success!"],
+                   {"type" : "text\/plain"}),
+        ];
+        let receivedMessageIndex = 0;
+
+        let mm = SpecialPowers.getBrowserFrameMessageManager(iframe);
+        mm.addMessageListener("test:ipcClonedMessage", SpecialPowers.wrapCallback(function(message) {
+          let data = message.json;
+
+          if (SpecialPowers.call_Instanceof(data, Blob)) {
+            is(receivedMessageIndex, messages.length - 1, "Blob is last");
+            is (data.size,
+                messages[receivedMessageIndex].size,
+                "Correct blob size");
+            is (data.type,
+                messages[receivedMessageIndex].type,
+                "Correct blob type");
+
+            let result1, result2;
+
+            let reader1 = new FileReader();
+            reader1.onload = function() {
+              result1 = reader1.result == blobString ? reader1.result : "bad1";
+              if (result2) {
+                is(result1, result2, "Same results");
+                done();
+              }
+            };
+
+            let reader2 = new FileReader();
+            reader2.onload = function() {
+              result2 = reader2.result == blobString ? reader2.result : "bad2";
+              if (result1) {
+                is(result1, result2, "Same results");
+                done();
+              }
+            };
+
+            SpecialPowers.wrap(reader1).readAsText(data);
+            reader2.readAsText(messages[receivedMessageIndex]);
+            return;
+          }
+
+          is(message.json,
+             messages[receivedMessageIndex++],
+             "Got correct round-tripped response");
+        }));
+        mm.loadFrameScript("data:,(" + childFrameScript.toString() + ")();",
+                           false);
+
+        for (let message of messages) {
+          mm.sendAsyncMessage("test:ipcClonedMessage", message);
+        }
+      });
+
+      document.body.appendChild(iframe);
+    }
+
+    addEventListener("load", function() {
+      info("Got load event.");
+
+      SpecialPowers.addPermission("browser", true, document);
+      SpecialPowers.pushPrefEnv({
+        "set": [
+          ["dom.ipc.browser_frames.oop_by_default", true],
+          ["dom.mozBrowserFramesEnabled", true],
+          ["network.disable.ipc.security", true],
+          ["browser.pagethumbnails.capturing_disabled", true]
+        ]
+      }, runTests);
+    });
+  </script>
+</body>
+</html>
diff --git a/dom/file/tests/test_ipc_messagemanager_blob.js b/dom/file/tests/test_ipc_messagemanager_blob.js
deleted file mode 100644
index 21f4b1c2697c..000000000000
--- a/dom/file/tests/test_ipc_messagemanager_blob.js
+++ /dev/null
@@ -1,99 +0,0 @@
-"use strict";
-
-const { ExtensionTestUtils } = ChromeUtils.import(
-  "resource://testing-common/ExtensionXPCShellUtils.jsm"
-);
-
-ExtensionTestUtils.init(this);
-
-function childFrameScript() {
-  addMessageListener("test:ipcClonedMessage", function(message) {
-    if (!Blob.isInstance(message.json)) {
-      sendAsyncMessage(message.name, message.json);
-      return;
-    }
-
-    let reader = new FileReader();
-    reader.addEventListener("load", function() {
-      let response =
-        reader.result == "this is a great success!" ? message.json : "error";
-      sendAsyncMessage(message.name, response);
-    });
-    reader.readAsText(message.json);
-  });
-}
-
-add_task(async function test() {
-  let page = await ExtensionTestUtils.loadContentPage("about:blank", {
-    remote: true,
-  });
-
-  page.loadFrameScript(childFrameScript);
-
-  const blobString = "this is a great success!";
-
-  const messages = [
-    "hi!",
-    "",
-    2,
-    -0.04,
-    3432987324987239872948732982,
-    true,
-    false,
-    null,
-    0,
-
-    // Make sure this one is always last.
-    new Blob(["this ", "is ", "a ", "great ", "success!"], {
-      type: "text/plain",
-    }),
-  ];
-  let receivedMessageIndex = 0;
-
-  let mm = page.browser.messageManager;
-  let done = new Promise(resolve => {
-    mm.addMessageListener("test:ipcClonedMessage", async message => {
-      let data = message.json;
-
-      if (Blob.isInstance(data)) {
-        equal(receivedMessageIndex, messages.length - 1, "Blob is last");
-        equal(
-          data.size,
-          messages[receivedMessageIndex].size,
-          "Correct blob size"
-        );
-        equal(
-          data.type,
-          messages[receivedMessageIndex].type,
-          "Correct blob type"
-        );
-
-        let reader1 = new FileReader();
-        reader1.readAsText(data);
-
-        let reader2 = new FileReader();
-        reader2.readAsText(messages[receivedMessageIndex]);
-
-        await Promise.all([
-          new Promise(res => (reader1.onload = res)),
-          new Promise(res => (reader2.onload = res)),
-        ]);
-
-        equal(reader1.result, blobString, "Result 1");
-        equal(reader2.result, blobString, "Result 2");
-
-        resolve();
-      } else {
-        equal(
-          data,
-          messages[receivedMessageIndex++],
-          "Got correct round-tripped response"
-        );
-      }
-    });
-  });
-
-  for (let message of messages) {
-    mm.sendAsyncMessage("test:ipcClonedMessage", message);
-  }
-});
diff --git a/dom/file/tests/xpcshell.ini b/dom/file/tests/xpcshell.ini
index 6f6891d15ae9..8a088e60cd62 100644
--- a/dom/file/tests/xpcshell.ini
+++ b/dom/file/tests/xpcshell.ini
@@ -2,4 +2,3 @@
 
 [test_bloburi.js]
 [test_createFile.js]
-[test_ipc_messagemanager_blob.js]
diff --git a/dom/html/nsGenericHTMLFrameElement.cpp b/dom/html/nsGenericHTMLFrameElement.cpp
index 051a811edff0..594feda97970 100644
--- a/dom/html/nsGenericHTMLFrameElement.cpp
+++ b/dom/html/nsGenericHTMLFrameElement.cpp
@@ -255,6 +255,17 @@ ScrollbarPreference nsGenericHTMLFrameElement::MapScrollingAttribute(
   return ScrollbarPreference::Auto;
 }
 
+static bool PrincipalAllowsBrowserFrame(nsIPrincipal* aPrincipal) {
+  nsCOMPtr<nsIPermissionManager> permMgr =
+      mozilla::services::GetPermissionManager();
+  NS_ENSURE_TRUE(permMgr, false);
+  uint32_t permission = nsIPermissionManager::DENY_ACTION;
+  nsresult rv = permMgr->TestPermissionFromPrincipal(
+      aPrincipal, NS_LITERAL_CSTRING("browser"), &permission);
+  NS_ENSURE_SUCCESS(rv, false);
+  return permission == nsIPermissionManager::ALLOW_ACTION;
+}
+
 /* virtual */
 nsresult nsGenericHTMLFrameElement::AfterSetAttr(
     int32_t aNameSpaceID, nsAtom* aName, const nsAttrValue* aValue,
@@ -285,9 +296,9 @@ nsresult nsGenericHTMLFrameElement::AfterSetAttr(
         }
       }
     } else if (aName == nsGkAtoms::mozbrowser) {
-      mReallyIsBrowser =
-          !!aValue && StaticPrefs::dom_mozBrowserFramesEnabled() &&
-          XRE_IsParentProcess() && NodePrincipal()->IsSystemPrincipal();
+      mReallyIsBrowser = !!aValue &&
+                         StaticPrefs::dom_mozBrowserFramesEnabled() &&
+                         PrincipalAllowsBrowserFrame(NodePrincipal());
     }
   }
 
diff --git a/dom/html/test/file_ignoreuserfocus.html b/dom/html/test/file_ignoreuserfocus.html
new file mode 100644
index 000000000000..b9e33021249f
--- /dev/null
+++ b/dom/html/test/file_ignoreuserfocus.html
@@ -0,0 +1,10 @@
+<!DOCTYPE HTML>
+<html>
+  <body>
+    <map name=a>
+      <area shape=rect coords=0,0,100,100 href=#fail>
+    </map>
+    <img usemap=#a src=image.png>
+    <input><iframe></iframe>
+  </body>
+</html>
diff --git a/dom/html/test/mochitest.ini b/dom/html/test/mochitest.ini
index 6f6275a7203d..863c0e74998b 100644
--- a/dom/html/test/mochitest.ini
+++ b/dom/html/test/mochitest.ini
@@ -178,6 +178,7 @@ support-files =
   image-allow-credentials.png^headers^
   nnc_lockup.gif
   reflect.js
+  file_ignoreuserfocus.html
   simpleFileOpener.js
   file_bug1166138_1x.png
   file_bug1166138_2x.png
@@ -519,6 +520,8 @@ skip-if = (toolkit == 'android') || ((os == 'win' || os == 'linux') && debug) #
 [test_track.html]
 [test_ul_attributes_reflection.html]
 [test_input_files_not_nsIFile.html]
+[test_ignoreuserfocus.html]
+skip-if = true # Firefox OS test disabled to enable Fission focus changes
 [test_fragment_form_pointer.html]
 [test_bug1682.html]
 [test_bug1823.html]
diff --git a/dom/html/test/test_ignoreuserfocus.html b/dom/html/test/test_ignoreuserfocus.html
new file mode 100644
index 000000000000..94984244ae97
--- /dev/null
+++ b/dom/html/test/test_ignoreuserfocus.html
@@ -0,0 +1,159 @@
+<!DOCTYPE HTML>
+<html>
+  <head>
+    <script src="/tests/SimpleTest/SimpleTest.js"></script>
+    <script src="/tests/SimpleTest/EventUtils.js"></script>
+    <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+  </head>
+  <body>
+    <script type="application/javascript">
+      "use strict";
+
+      SimpleTest.requestCompleteLog();
+      SimpleTest.waitForExplicitFinish();
+
+      // Copied from EventUtils.js, but we want *ToWindow methods.
+      function synthesizeMouseAtPoint(left, top, aEvent, aWindow) {
+        var utils = _getDOMWindowUtils(aWindow);
+        var defaultPrevented = false;
+        if (utils) {
+          var button = aEvent.button || 0;
+          var clickCount = aEvent.clickCount || 1;
+          var modifiers = _parseModifiers(aEvent);
+          var pressure = ("pressure" in aEvent) ? aEvent.pressure : 0;
+          var inputSource = ("inputSource" in aEvent) ? aEvent.inputSource : 0;
+
+          if (("type" in aEvent) && aEvent.type) {
+            defaultPrevented = utils.sendMouseEventToWindow(aEvent.type, left, top, button, clickCount, modifiers, false, pressure, inputSource);
+          }
+          else {
+            utils.sendMouseEventToWindow("mousedown", left, top, button, clickCount, modifiers, false, pressure, inputSource);
+            utils.sendMouseEventToWindow("mouseup", left, top, button, clickCount, modifiers, false, pressure, inputSource);
+          }
+        }
+      }
+
+      function runTest() {
+        var witness = document.createElement("input");
+        witness.setAttribute("type", "text");
+        var witness2 = document.createElement("input");
+        witness2.setAttribute("type", "text");
+
+        var iframe = document.createElement("iframe");
+        iframe.setAttribute("mozbrowser", "true");
+        iframe.setAttribute("ignoreuserfocus", "true");
+        iframe.setAttribute("height", "300px");
+
+        iframe.addEventListener('mozbrowserloadend', function (e) {
+          // Get privileged iframe because mozbrowser iframe is not same origin
+          // with the parent. We need to access its content through the wrapper.
+          var privilegedIframe = SpecialPowers.wrap(iframe);
+          if (!privilegedIframe.contentWindow.location.href.endsWith("file_ignoreuserfocus.html")) {
+            return;
+          }
+
+          privilegedIframe.contentWindow.addEventListener("MozAfterPaint", function() {
+            privilegedIframe.contentWindow.addEventListener("focus",
+              function() {
+                ok(!iframe.hasAttribute("ignoreuserfocus"), "Shouldn't get a focus event in ignoreuserfocus iframe!");
+              },
+              true);
+            privilegedIframe.contentWindow.addEventListener("blur",
+              function() {
+                ok(!iframe.hasAttribute("ignoreuserfocus"), "Shouldn't get a blur event in ignoreuserfocus iframe!");
+              },
+              true);
+
+            // Sanity check
+            witness.focus();
+            is(document.activeElement, witness, "witness should have the focus");
+
+            iframe.focus();
+            isnot(document.activeElement, iframe, "[explicit iframe.focus()] iframe should not get the focus");
+
+            iframe.removeAttribute("ignoreuserfocus");
+            iframe.focus();
+            is(document.activeElement, iframe, "[explicit iframe.focus()] iframe should get the focus");
+
+            iframe.setAttribute("ignoreuserfocus", "true");
+
+            // Test the case when iframe contains <input> and .focus()
+            // is called and explicit focus using mouse
+            witness.focus();
+
+            var innerInput = privilegedIframe.contentDocument.getElementsByTagName("input")[0];
+            innerInput.focus();
+            isnot(document.activeElement, iframe, "[explicit innerInput.focus()] iframe should not have the focus");
+
+            var iframeWindow = SpecialPowers.unwrap(privilegedIframe.contentWindow);
+            witness.focus();
+            synthesizeMouseAtCenter(innerInput, {}, iframeWindow);
+            is(document.activeElement, witness, "[synthesize mouse click] witness should have the focus");
+
+            // Test the case when iframe contains <iframe> and .focus()
+            // is called and explicit focus using mouse
+            witness.focus();
+
+            var innerIframe = privilegedIframe.contentDocument.getElementsByTagName("iframe")[0];
+            innerIframe.focus();
+            isnot(document.activeElement, iframe, "[explicit innerIframe.focus()] iframe should not have the focus");
+
+            witness.focus();
+            synthesizeMouseAtCenter(innerIframe, {}, iframeWindow);
+            is(document.activeElement, witness, "[synthesize mouse click inner iframe] witness should have the focus");
+
+            // Test the case when iframe contains <area> and .focus()
+            // is called and explicit focus using mouse
+
+            // Wait for paint to setup frame for area. Currently the area frame
+            // map is reset for each paint. If we are in the middle of a paint
+            // then the area will not be focusable.
+            privilegedIframe.contentWindow.addEventListener("MozAfterPaint", function() {
+              var innerArea = privilegedIframe.contentDocument.getElementsByTagName("area")[0];
+              innerArea.focus();
+              isnot(document.activeElement, iframe, "[explicit innerArea.focus()] iframe should not have the focus");
+
+              witness.focus();
+              synthesizeMouseAtCenter(innerArea, {}, iframeWindow);
+              is(document.activeElement, witness, "[synthesize mouse click] witness should have the focus");
+
+              // Test tabindex
+              witness.focus();
+              is(document.activeElement, witness, "witness should have the focus");
+              synthesizeKey("KEY_Tab");
+              isnot(document.activeElement, iframe, "[synthesize tab key] iframe should not have the focus");
+              is(document.activeElement, witness2, "witness2 should have the focus");
+
+              SimpleTest.finish();
+            }, {once: true});
+            witness.focus();
+            // force reflow
+            iframe.setAttribute("height", "298px");
+          }, {once: true});
+          // force reflow
+          iframe.setAttribute("height", "299px");
+        });
+
+        document.body.appendChild(witness);
+        document.body.appendChild(iframe);
+        document.body.appendChild(witness2);
+
+        iframe.setAttribute("src", "file_ignoreuserfocus.html");
+      }
+      addEventListener("load", function() {
+        SpecialPowers.pushPermissions(
+          [{'type': 'browser', 'allow': true, 'context': document}],
+          function() {
+            SpecialPowers.pushPrefEnv({
+              "set": [
+                ["dom.mozBrowserFramesEnabled", true],
+                ["network.disable.ipc.security", true],
+              ]
+            }, function() {
+              SimpleTest.waitForFocus(runTest);
+            });
+          });
+      });
+    </script>
+  </body>
+</html>
diff --git a/dom/indexedDB/test/mochitest.ini b/dom/indexedDB/test/mochitest.ini
index ddfcfd808ea3..67e35020cd31 100644
--- a/dom/indexedDB/test/mochitest.ini
+++ b/dom/indexedDB/test/mochitest.ini
@@ -215,6 +215,8 @@ skip-if = true
 [test_leaving_page.html]
 [test_maximal_serialized_object_size.html]
 [test_message_manager_ipc.html]
+# This test is only supposed to run in the main process.
+skip-if = e10s
 [test_multientry.html]
 [test_names_sorted.html]
 [test_objectCursors.html]
diff --git a/dom/indexedDB/test/test_message_manager_ipc.html b/dom/indexedDB/test/test_message_manager_ipc.html
index bf26618c346a..9eb6488e9bb3 100644
--- a/dom/indexedDB/test/test_message_manager_ipc.html
+++ b/dom/indexedDB/test/test_message_manager_ipc.html
@@ -6,217 +6,201 @@
     </script>
     <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
   </head>
-  <body>
+  <body onload="setup();">
     <script type="application/javascript">
 "use strict";
 
-async function chromeScriptFunc() {
-  function childFrameScript() {
-    /* eslint-env mozilla/frame-script */
-    "use strict";
+function childFrameScript() {
+  /* eslint-env mozilla/frame-script */
+  "use strict";
 
-    const mmName = "test:idb-and-mm";
+  const mmName = "test:idb-and-mm";
 
-    const dbName = "test_message_manager_ipc.html - CHILD";
-    const dbVersion = 1;
-    const objStoreName = "bar";
-    const key = 1;
+  const dbName = "test_message_manager_ipc.html - CHILD";
+  const dbVersion = 1;
+  const objStoreName = "bar";
+  const key = 1;
 
-    const blobData = ["So", " ", "many", " ", "blobs!"];
-    const blobText = blobData.join("");
-    const blobType = "text/plain";
+  const blobData = ["So", " ", "many", " ", "blobs!"];
+  const blobText = blobData.join("");
+  const blobType = "text/plain";
 
-    Cu.importGlobalProperties(["indexedDB"]);
+  Cu.importGlobalProperties(["indexedDB"]);
 
-    function info(msg) {
-      sendAsyncMessage(mmName, { op: "info", msg });
-    }
-
-    function ok(condition, name, diag) {
-      sendAsyncMessage(mmName,
-                       { op: "ok",
-                         condition,
-                         name,
-                         diag });
-    }
-
-    function is(a, b, name) {
-      let pass = a == b;
-      let diag = pass ? "" : "got " + a + ", expected " + b;
-      ok(pass, name, diag);
-    }
-
-    function finish(result) {
-      sendAsyncMessage(mmName, { op: "done", result });
-    }
-
-    function grabAndContinue(arg) {
-      testGenerator.next(arg);
-    }
-
-    function errorHandler(event) {
-      ok(false,
-         event.target + " received error event: '" + event.target.error.name +
-         "'");
-      finish();
-    }
-
-    function* testSteps() {
-      addMessageListener(mmName, grabAndContinue);
-      let message = yield undefined;
-
-      let blob = message.data;
-
-      ok(Blob.isInstance(blob), "Message manager sent a blob");
-      is(blob.size, blobText.length, "Blob has correct length");
-      is(blob.type, blobType, "Blob has correct type");
-
-      info("Reading blob");
-
-      let reader = new FileReader();
-      reader.addEventListener("load", grabAndContinue);
-      reader.readAsText(blob);
-
-      yield undefined;
-
-      is(reader.result, blobText, "Blob has correct data");
-
-      let slice = blob.slice(0, blobData[0].length, blobType);
-
-      ok(Blob.isInstance(slice), "Slice returned a blob");
-      is(slice.size, blobData[0].length, "Slice has correct length");
-      is(slice.type, blobType, "Slice has correct type");
-
-      info("Reading slice");
-
-      reader = new FileReader();
-      reader.addEventListener("load", grabAndContinue);
-      reader.readAsText(slice);
-
-      yield undefined;
-
-      is(reader.result, blobData[0], "Slice has correct data");
-
-      info("Deleting database");
-
-      let req = indexedDB.deleteDatabase(dbName);
-      req.onerror = errorHandler;
-      req.onsuccess = grabAndContinue;
-
-      let event = yield undefined;
-      is(event.type, "success", "Got success event");
-
-      info("Opening database");
-
-      req = indexedDB.open(dbName, dbVersion);
-      req.onerror = errorHandler;
-      req.onupgradeneeded = grabAndContinue;
-      req.onsuccess = grabAndContinue;
-
-      event = yield undefined;
-      is(event.type, "upgradeneeded", "Got upgradeneeded event");
-
-      event.target.result.createObjectStore(objStoreName);
-
-      event = yield undefined;
-      is(event.type, "success", "Got success event");
-
-      let db = event.target.result;
-
-      info("Storing blob from message manager in database");
-
-      let objectStore =
-        db.transaction(objStoreName, "readwrite").objectStore(objStoreName);
-      req = objectStore.add(blob, key);
-      req.onerror = errorHandler;
-      req.onsuccess = grabAndContinue;
-
-      event = yield undefined;
-
-      info("Getting blob from database");
-
-      objectStore = db.transaction(objStoreName).objectStore(objStoreName);
-      req = objectStore.get(key);
-      req.onerror = errorHandler;
-      req.onsuccess = grabAndContinue;
-
-      event = yield undefined;
-
-      blob = event.target.result;
-
-      ok(Blob.isInstance(blob), "Database gave us a blob");
-      is(blob.size, blobText.length, "Blob has correct length");
-      is(blob.type, blobType, "Blob has correct type");
-
-      info("Reading blob");
-
-      reader = new FileReader();
-      reader.addEventListener("load", grabAndContinue);
-      reader.readAsText(blob);
-
-      yield undefined;
-
-      is(reader.result, blobText, "Blob has correct data");
-
-      info("Storing slice from message manager in database");
-
-      objectStore =
-        db.transaction(objStoreName, "readwrite").objectStore(objStoreName);
-      req = objectStore.put(slice, key);
-      req.onerror = errorHandler;
-      req.onsuccess = grabAndContinue;
-
-      event = yield undefined;
-
-      info("Getting slice from database");
-
-      objectStore = db.transaction(objStoreName).objectStore(objStoreName);
-      req = objectStore.get(key);
-      req.onerror = errorHandler;
-      req.onsuccess = grabAndContinue;
-
-      event = yield undefined;
-
-      slice = event.target.result;
-
-      ok(Blob.isInstance(slice), "Database gave us a blob");
-      is(slice.size, blobData[0].length, "Slice has correct length");
-      is(slice.type, blobType, "Slice has correct type");
-
-      info("Reading Slice");
-
-      reader = new FileReader();
-      reader.addEventListener("load", grabAndContinue);
-      reader.readAsText(slice);
-
-      yield undefined;
-
-      is(reader.result, blobData[0], "Slice has correct data");
-
-      info("Sending blob and slice from database to message manager");
-      finish([blob, slice]);
-    }
-
-    let testGenerator = testSteps();
-    testGenerator.next();
+  function info(msg) {
+    sendAsyncMessage(mmName, { op: "info", msg });
   }
 
-  /* globals Services, createWindowlessBrowser */
-  let { windowlessBrowser, browser } = await createWindowlessBrowser();
-
-  const system = Services.scriptSecurityManager.getSystemPrincipal();
-  browser.loadURI(
-    "data:text/html,<!DOCTYPE HTML><html><body></body></html>",
-    { triggeringPrincipal: system }
-  );
-
-  function finish() {
-    sendAsyncMessage("done");
-    windowlessBrowser.close();
+  function ok(condition, name, diag) {
+    sendAsyncMessage(mmName,
+                     { op: "ok",
+                       condition,
+                       name,
+                       diag });
   }
 
-  let mm = browser.messageManager;
+  function is(a, b, name) {
+    let pass = a == b;
+    let diag = pass ? "" : "got " + a + ", expected " + b;
+    ok(pass, name, diag);
+  }
 
+  function finish(result) {
+    sendAsyncMessage(mmName, { op: "done", result });
+  }
+
+  function grabAndContinue(arg) {
+    testGenerator.next(arg);
+  }
+
+  function errorHandler(event) {
+    ok(false,
+       event.target + " received error event: '" + event.target.error.name +
+       "'");
+    finish();
+  }
+
+  function* testSteps() {
+    addMessageListener(mmName, grabAndContinue);
+    let message = yield undefined;
+
+    let blob = message.data;
+
+    ok(Blob.isInstance(blob), "Message manager sent a blob");
+    is(blob.size, blobText.length, "Blob has correct length");
+    is(blob.type, blobType, "Blob has correct type");
+
+    info("Reading blob");
+
+    let reader = new FileReader();
+    reader.addEventListener("load", grabAndContinue);
+    reader.readAsText(blob);
+
+    yield undefined;
+
+    is(reader.result, blobText, "Blob has correct data");
+
+    let slice = blob.slice(0, blobData[0].length, blobType);
+
+    ok(Blob.isInstance(slice), "Slice returned a blob");
+    is(slice.size, blobData[0].length, "Slice has correct length");
+    is(slice.type, blobType, "Slice has correct type");
+
+    info("Reading slice");
+
+    reader = new FileReader();
+    reader.addEventListener("load", grabAndContinue);
+    reader.readAsText(slice);
+
+    yield undefined;
+
+    is(reader.result, blobData[0], "Slice has correct data");
+
+    info("Deleting database");
+
+    let req = indexedDB.deleteDatabase(dbName);
+    req.onerror = errorHandler;
+    req.onsuccess = grabAndContinue;
+
+    let event = yield undefined;
+    is(event.type, "success", "Got success event");
+
+    info("Opening database");
+
+    req = indexedDB.open(dbName, dbVersion);
+    req.onerror = errorHandler;
+    req.onupgradeneeded = grabAndContinue;
+    req.onsuccess = grabAndContinue;
+
+    event = yield undefined;
+    is(event.type, "upgradeneeded", "Got upgradeneeded event");
+
+    event.target.result.createObjectStore(objStoreName);
+
+    event = yield undefined;
+    is(event.type, "success", "Got success event");
+
+    let db = event.target.result;
+
+    info("Storing blob from message manager in database");
+
+    let objectStore =
+      db.transaction(objStoreName, "readwrite").objectStore(objStoreName);
+    req = objectStore.add(blob, key);
+    req.onerror = errorHandler;
+    req.onsuccess = grabAndContinue;
+
+    event = yield undefined;
+
+    info("Getting blob from database");
+
+    objectStore = db.transaction(objStoreName).objectStore(objStoreName);
+    req = objectStore.get(key);
+    req.onerror = errorHandler;
+    req.onsuccess = grabAndContinue;
+
+    event = yield undefined;
+
+    blob = event.target.result;
+
+    ok(Blob.isInstance(blob), "Database gave us a blob");
+    is(blob.size, blobText.length, "Blob has correct length");
+    is(blob.type, blobType, "Blob has correct type");
+
+    info("Reading blob");
+
+    reader = new FileReader();
+    reader.addEventListener("load", grabAndContinue);
+    reader.readAsText(blob);
+
+    yield undefined;
+
+    is(reader.result, blobText, "Blob has correct data");
+
+    info("Storing slice from message manager in database");
+
+    objectStore =
+      db.transaction(objStoreName, "readwrite").objectStore(objStoreName);
+    req = objectStore.put(slice, key);
+    req.onerror = errorHandler;
+    req.onsuccess = grabAndContinue;
+
+    event = yield undefined;
+
+    info("Getting slice from database");
+
+    objectStore = db.transaction(objStoreName).objectStore(objStoreName);
+    req = objectStore.get(key);
+    req.onerror = errorHandler;
+    req.onsuccess = grabAndContinue;
+
+    event = yield undefined;
+
+    slice = event.target.result;
+
+    ok(Blob.isInstance(slice), "Database gave us a blob");
+    is(slice.size, blobData[0].length, "Slice has correct length");
+    is(slice.type, blobType, "Slice has correct type");
+
+    info("Reading Slice");
+
+    reader = new FileReader();
+    reader.addEventListener("load", grabAndContinue);
+    reader.readAsText(slice);
+
+    yield undefined;
+
+    is(reader.result, blobData[0], "Slice has correct data");
+
+    info("Sending blob and slice from database to message manager");
+    finish([blob, slice]);
+  }
+
+  let testGenerator = testSteps();
+  testGenerator.next();
+}
+
+function parentFrameScript(mm) {
   const messageName = "test:idb-and-mm";
   const blobData = ["So", " ", "many", " ", "blobs!"];
   const blobText = blobData.join("");
@@ -230,16 +214,16 @@ async function chromeScriptFunc() {
   function* testSteps() {
     let result = yield undefined;
 
-    is(Cu.getClassName(result, true), "Array", "Child delivered an array of results");
+    is(SpecialPowers.Cu.getClassName(result, true), "Array", "Child delivered an array of results");
     is(result.length, 2, "Child delivered two results");
 
     let blob = result[0];
-    is(Blob.isInstance(blob), true, "Child delivered a blob");
+    is(SpecialPowers.call_Instanceof(blob, Blob), true, "Child delivered a blob");
     is(blob.size, blobText.length, "Blob has correct size");
     is(blob.type, blobType, "Blob has correct type");
 
     let slice = result[1];
-    is(Blob.isInstance(slice), true, "Child delivered a slice");
+    is(SpecialPowers.call_Instanceof(slice, Blob), true, "Child delivered a slice");
     is(slice.size, blobData[0].length, "Slice has correct size");
     is(slice.type, blobType, "Slice has correct type");
 
@@ -247,7 +231,7 @@ async function chromeScriptFunc() {
 
     let reader = new FileReader();
     reader.onload = grabAndContinue;
-    reader.readAsText(blob);
+    SpecialPowers.wrap(reader).readAsText(blob);
     yield undefined;
 
     is(reader.result, blobText, "Blob has correct data");
@@ -256,14 +240,14 @@ async function chromeScriptFunc() {
 
     reader = new FileReader();
     reader.onload = grabAndContinue;
-    reader.readAsText(slice);
+    SpecialPowers.wrap(reader).readAsText(slice);
     yield undefined;
 
     is(reader.result, blobData[0], "Slice has correct data");
 
     slice = blob.slice(0, blobData[0].length, blobType);
 
-    is(Blob.isInstance(slice), true, "Child delivered a slice");
+    is(SpecialPowers.call_Instanceof(slice, Blob), true, "Child delivered a slice");
     is(slice.size, blobData[0].length, "Second slice has correct size");
     is(slice.type, blobType, "Second slice has correct type");
 
@@ -271,18 +255,18 @@ async function chromeScriptFunc() {
 
     reader = new FileReader();
     reader.onload = grabAndContinue;
-    reader.readAsText(slice);
+    SpecialPowers.wrap(reader).readAsText(slice);
     yield undefined;
 
     is(reader.result, blobData[0], "Second slice has correct data");
 
-    finish();
+    SimpleTest.finish();
   }
 
   let testGenerator = testSteps();
   testGenerator.next();
 
-  mm.addMessageListener(messageName, function(message) {
+  mm.addMessageListener(messageName, SpecialPowers.wrapCallback(function(message) {
     let data = message.data;
     switch (data.op) {
       case "info": {
@@ -302,22 +286,54 @@ async function chromeScriptFunc() {
 
       default: {
         ok(false, "Unknown op: " + data.op);
-        finish();
+        SimpleTest.finish();
       }
     }
-  });
+  }));
 
-  mm.loadFrameScript(`data:,(${childFrameScript})();`,
+  mm.loadFrameScript("data:,(" + childFrameScript.toString() + ")();",
                       false);
 
   mm.sendAsyncMessage(messageName, blob);
 }
 
-add_task(async function() {
-  let chromeScript = SpecialPowers.loadChromeScript(chromeScriptFunc);
-  await chromeScript.promiseOneMessage("done");
-  await chromeScript.destroy();
-});
+function setup() {
+  info("Got load event");
+
+  SpecialPowers.pushPrefEnv(
+    { set: [ ["dom.ipc.browser_frames.oop_by_default", true],
+              ["dom.mozBrowserFramesEnabled", true],
+              ["network.disable.ipc.security", true],
+              ["browser.pagethumbnails.capturing_disabled", true] ] },
+    function() {
+      info("Prefs set");
+
+      SpecialPowers.pushPermissions(
+        [ { type: "browser", allow: true, context: document } ],
+        function() {
+          info("Permissions set");
+
+          let iframe = document.createElement("iframe");
+          SpecialPowers.wrap(iframe).mozbrowser = true;
+          iframe.id = "iframe";
+          iframe.src =
+            "data:text/html,<!DOCTYPE HTML><html><body></body></html>";
+
+          iframe.addEventListener("mozbrowserloadend", function() {
+            info("Starting tests");
+
+            let mm = SpecialPowers.getBrowserFrameMessageManager(iframe);
+            parentFrameScript(mm);
+          });
+
+          document.body.appendChild(iframe);
+        }
+      );
+    }
+  );
+}
+
+SimpleTest.waitForExplicitFinish();
     </script>
   </body>
 </html>
diff --git a/dom/ipc/BrowserBridgeParent.cpp b/dom/ipc/BrowserBridgeParent.cpp
index 398d756e06c2..9b3ee91bd70b 100644
--- a/dom/ipc/BrowserBridgeParent.cpp
+++ b/dom/ipc/BrowserBridgeParent.cpp
@@ -49,7 +49,7 @@ nsresult BrowserBridgeParent::InitWithProcess(
         true, principal->OriginAttributesRef().mFirstPartyDomain);
   }
 
-  tabContext.SetTabContext(Manager()->ChromeOuterWindowID(),
+  tabContext.SetTabContext(false, Manager()->ChromeOuterWindowID(),
                            Manager()->ShowFocusRings(), attrs, aPresentationURL,
                            Manager()->GetMaxTouchPoints());
 
diff --git a/dom/ipc/BrowserChild.cpp b/dom/ipc/BrowserChild.cpp
index 62c1f37f4fce..1c8a6e0fdbd3 100644
--- a/dom/ipc/BrowserChild.cpp
+++ b/dom/ipc/BrowserChild.cpp
@@ -143,6 +143,9 @@
 #  include "nsIWebBrowserPrint.h"
 #endif
 
+#define BROWSER_ELEMENT_CHILD_SCRIPT \
+  NS_LITERAL_STRING("chrome://global/content/BrowserElementChild.js")
+
 static mozilla::LazyLogModule sApzChildLog("apz.child");
 
 using namespace mozilla;
@@ -198,7 +201,7 @@ void BrowserChild::DispatchMessageManagerMessage(const nsAString& aMessageName,
       mBrowserChildMessageManager);
   RefPtr<nsFrameMessageManager> mm = kungFuDeathGrip->GetMessageManager();
   mm->ReceiveMessage(static_cast<EventTarget*>(kungFuDeathGrip), nullptr,
-                     aMessageName, false, &data, nullptr, nullptr,
+                     aMessageName, false, &data, nullptr, nullptr, nullptr,
                      IgnoreErrors());
 }
 
@@ -593,12 +596,24 @@ void BrowserChild::NotifyTabContextUpdated() {
     return;
   }
 
+  UpdateFrameType();
+
   // Set SANDBOXED_AUXILIARY_NAVIGATION flag if this is a receiver page.
   if (!PresentationURL().IsEmpty()) {
     mBrowsingContext->SetSandboxFlags(SANDBOXED_AUXILIARY_NAVIGATION);
   }
 }
 
+void BrowserChild::UpdateFrameType() {
+  nsCOMPtr<nsIDocShell> docShell = do_GetInterface(WebNavigation());
+  MOZ_ASSERT(docShell);
+
+  // TODO: Bug 1252794 - remove frameType from nsIDocShell.idl
+  docShell->SetFrameType(IsMozBrowserElement()
+                             ? nsIDocShell::FRAME_TYPE_BROWSER
+                             : nsIDocShell::FRAME_TYPE_REGULAR);
+}
+
 NS_IMPL_CYCLE_COLLECTION_CLASS(BrowserChild)
 
 NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(BrowserChild)
@@ -1081,6 +1096,9 @@ void BrowserChild::ApplyParentShowInfo(const ParentShowInfo& aInfo) {
     mDidSetRealShowInfo = true;
   }
 
+  if (nsCOMPtr<nsIDocShell> docShell = do_GetInterface(WebNavigation())) {
+    docShell->SetFullscreenAllowed(aInfo.fullscreenAllowed());
+  }
   mIsTransparent = aInfo.isTransparent();
 }
 
@@ -2180,7 +2198,7 @@ mozilla::ipc::IPCResult BrowserChild::RecvLoadRemoteScript(
 
 mozilla::ipc::IPCResult BrowserChild::RecvAsyncMessage(
     const nsString& aMessage, nsTArray<CpowEntry>&& aCpows,
-    const ClonedMessageData& aData) {
+    nsIPrincipal* aPrincipal, const ClonedMessageData& aData) {
   AUTO_PROFILER_LABEL_DYNAMIC_LOSSY_NSSTRING("BrowserChild::RecvAsyncMessage",
                                              OTHER, aMessage);
   MMPrinter::Print("BrowserChild::RecvAsyncMessage", aMessage, aData);
@@ -2206,8 +2224,8 @@ mozilla::ipc::IPCResult BrowserChild::RecvAsyncMessage(
   StructuredCloneData data;
   UnpackClonedMessageDataForChild(aData, data);
   mm->ReceiveMessage(static_cast<EventTarget*>(mBrowserChildMessageManager),
-                     nullptr, aMessage, false, &data, &cpows, nullptr,
-                     IgnoreErrors());
+                     nullptr, aMessage, false, &data, &cpows, aPrincipal,
+                     nullptr, IgnoreErrors());
   return IPC_OK();
 }
 
@@ -2249,8 +2267,17 @@ mozilla::ipc::IPCResult BrowserChild::RecvSwappedWithOtherRemoteLoader(
     MOZ_CRASH("Update to TabContext after swap was denied.");
   }
 
+  // Since mIsMozBrowserElement may change in UpdateTabContextAfterSwap, so we
+  // call UpdateFrameType here to make sure the frameType on the docshell is
+  // correct.
+  UpdateFrameType();
+
   // Ignore previous value of mTriedBrowserInit since owner content has changed.
   mTriedBrowserInit = true;
+  // Initialize the child side of the browser element machinery, if appropriate.
+  if (IsMozBrowserElement()) {
+    RecvLoadRemoteScript(BROWSER_ELEMENT_CHILD_SCRIPT, true);
+  }
 
   nsContentUtils::FirePageShowEventForFrameLoaderSwap(
       ourDocShell, ourEventTarget, true, true);
@@ -2597,6 +2624,11 @@ bool BrowserChild::InitBrowserChildMessageManager() {
 
   if (!mTriedBrowserInit) {
     mTriedBrowserInit = true;
+    // Initialize the child side of the browser element machinery,
+    // if appropriate.
+    if (IsMozBrowserElement()) {
+      RecvLoadRemoteScript(BROWSER_ELEMENT_CHILD_SCRIPT, true);
+    }
   }
 
   return true;
@@ -2920,12 +2952,10 @@ void BrowserChild::SetTabId(const TabId& aTabId) {
   NestedBrowserChildMap()[mUniqueId] = this;
 }
 
-bool BrowserChild::DoSendBlockingMessage(JSContext* aCx,
-                                         const nsAString& aMessage,
-                                         StructuredCloneData& aData,
-                                         JS::Handle<JSObject*> aCpows,
-                                         nsTArray<StructuredCloneData>* aRetVal,
-                                         bool aIsSync) {
+bool BrowserChild::DoSendBlockingMessage(
+    JSContext* aCx, const nsAString& aMessage, StructuredCloneData& aData,
+    JS::Handle<JSObject*> aCpows, nsIPrincipal* aPrincipal,
+    nsTArray<StructuredCloneData>* aRetVal, bool aIsSync) {
   ClonedMessageData data;
   if (!BuildClonedMessageDataForChild(Manager(), aData, data)) {
     return false;
@@ -2938,16 +2968,19 @@ bool BrowserChild::DoSendBlockingMessage(JSContext* aCx,
     }
   }
   if (aIsSync) {
-    return SendSyncMessage(PromiseFlatString(aMessage), data, cpows, aRetVal);
+    return SendSyncMessage(PromiseFlatString(aMessage), data, cpows, aPrincipal,
+                           aRetVal);
   }
 
-  return SendRpcMessage(PromiseFlatString(aMessage), data, cpows, aRetVal);
+  return SendRpcMessage(PromiseFlatString(aMessage), data, cpows, aPrincipal,
+                        aRetVal);
 }
 
 nsresult BrowserChild::DoSendAsyncMessage(JSContext* aCx,
                                           const nsAString& aMessage,
                                           StructuredCloneData& aData,
-                                          JS::Handle<JSObject*> aCpows) {
+                                          JS::Handle<JSObject*> aCpows,
+                                          nsIPrincipal* aPrincipal) {
   ClonedMessageData data;
   if (!BuildClonedMessageDataForChild(Manager(), aData, data)) {
     return NS_ERROR_DOM_DATA_CLONE_ERR;
@@ -2959,7 +2992,7 @@ nsresult BrowserChild::DoSendAsyncMessage(JSContext* aCx,
       return NS_ERROR_UNEXPECTED;
     }
   }
-  if (!SendAsyncMessage(PromiseFlatString(aMessage), cpows, data)) {
+  if (!SendAsyncMessage(PromiseFlatString(aMessage), cpows, aPrincipal, data)) {
     return NS_ERROR_UNEXPECTED;
   }
   return NS_OK;
diff --git a/dom/ipc/BrowserChild.h b/dom/ipc/BrowserChild.h
index 694ecaf9d890..6c3cd3279bf4 100644
--- a/dom/ipc/BrowserChild.h
+++ b/dom/ipc/BrowserChild.h
@@ -227,6 +227,7 @@ class BrowserChild final : public nsMessageManagerScriptExecutor,
     return mBrowserChildMessageManager->WrapObject(aCx, aGivenProto);
   }
 
+  nsIPrincipal* GetPrincipal() { return mPrincipal; }
   // Get the Document for the top-level window in this tab.
   already_AddRefed<Document> GetTopLevelDocument() const;
 
@@ -245,12 +246,14 @@ class BrowserChild final : public nsMessageManagerScriptExecutor,
   virtual bool DoSendBlockingMessage(JSContext* aCx, const nsAString& aMessage,
                                      StructuredCloneData& aData,
                                      JS::Handle<JSObject*> aCpows,
+                                     nsIPrincipal* aPrincipal,
                                      nsTArray<StructuredCloneData>* aRetVal,
                                      bool aIsSync) override;
 
   virtual nsresult DoSendAsyncMessage(JSContext* aCx, const nsAString& aMessage,
                                       StructuredCloneData& aData,
-                                      JS::Handle<JSObject*> aCpows) override;
+                                      JS::Handle<JSObject*> aCpows,
+                                      nsIPrincipal* aPrincipal) override;
 
   bool DoUpdateZoomConstraints(const uint32_t& aPresShellId,
                                const ViewID& aViewId,
@@ -414,6 +417,7 @@ class BrowserChild final : public nsMessageManagerScriptExecutor,
 
   mozilla::ipc::IPCResult RecvAsyncMessage(const nsString& aMessage,
                                            nsTArray<CpowEntry>&& aCpows,
+                                           nsIPrincipal* aPrincipal,
                                            const ClonedMessageData& aData);
   mozilla::ipc::IPCResult RecvSwappedWithOtherRemoteLoader(
       const IPCTabContext& aContext);
@@ -770,6 +774,9 @@ class BrowserChild final : public nsMessageManagerScriptExecutor,
   // call this during Init().
   void NotifyTabContextUpdated();
 
+  // Update the frameType on our docshell.
+  void UpdateFrameType();
+
   void ActorDestroy(ActorDestroyReason why) override;
 
   bool InitBrowserChildMessageManager();
diff --git a/dom/ipc/BrowserParent.cpp b/dom/ipc/BrowserParent.cpp
index 89c3421fa84c..0335555069a1 100644
--- a/dom/ipc/BrowserParent.cpp
+++ b/dom/ipc/BrowserParent.cpp
@@ -2034,7 +2034,8 @@ bool BrowserParent::SendHandleTap(TapType aType,
 
 mozilla::ipc::IPCResult BrowserParent::RecvSyncMessage(
     const nsString& aMessage, const ClonedMessageData& aData,
-    nsTArray<CpowEntry>&& aCpows, nsTArray<StructuredCloneData>* aRetVal) {
+    nsTArray<CpowEntry>&& aCpows, nsIPrincipal* aPrincipal,
+    nsTArray<StructuredCloneData>* aRetVal) {
   AUTO_PROFILER_LABEL_DYNAMIC_LOSSY_NSSTRING("BrowserParent::RecvSyncMessage",
                                              OTHER, aMessage);
   MMPrinter::Print("BrowserParent::RecvSyncMessage", aMessage, aData);
@@ -2043,7 +2044,7 @@ mozilla::ipc::IPCResult BrowserParent::RecvSyncMessage(
   ipc::UnpackClonedMessageDataForParent(aData, data);
 
   CrossProcessCpowHolder cpows(Manager(), aCpows);
-  if (!ReceiveMessage(aMessage, true, &data, &cpows, aRetVal)) {
+  if (!ReceiveMessage(aMessage, true, &data, &cpows, aPrincipal, aRetVal)) {
     return IPC_FAIL_NO_REASON(this);
   }
   return IPC_OK();
@@ -2051,7 +2052,8 @@ mozilla::ipc::IPCResult BrowserParent::RecvSyncMessage(
 
 mozilla::ipc::IPCResult BrowserParent::RecvRpcMessage(
     const nsString& aMessage, const ClonedMessageData& aData,
-    nsTArray<CpowEntry>&& aCpows, nsTArray<StructuredCloneData>* aRetVal) {
+    nsTArray<CpowEntry>&& aCpows, nsIPrincipal* aPrincipal,
+    nsTArray<StructuredCloneData>* aRetVal) {
   AUTO_PROFILER_LABEL_DYNAMIC_LOSSY_NSSTRING("BrowserParent::RecvRpcMessage",
                                              OTHER, aMessage);
   MMPrinter::Print("BrowserParent::RecvRpcMessage", aMessage, aData);
@@ -2060,7 +2062,7 @@ mozilla::ipc::IPCResult BrowserParent::RecvRpcMessage(
   ipc::UnpackClonedMessageDataForParent(aData, data);
 
   CrossProcessCpowHolder cpows(Manager(), aCpows);
-  if (!ReceiveMessage(aMessage, true, &data, &cpows, aRetVal)) {
+  if (!ReceiveMessage(aMessage, true, &data, &cpows, aPrincipal, aRetVal)) {
     return IPC_FAIL_NO_REASON(this);
   }
   return IPC_OK();
@@ -2068,7 +2070,7 @@ mozilla::ipc::IPCResult BrowserParent::RecvRpcMessage(
 
 mozilla::ipc::IPCResult BrowserParent::RecvAsyncMessage(
     const nsString& aMessage, nsTArray<CpowEntry>&& aCpows,
-    const ClonedMessageData& aData) {
+    nsIPrincipal* aPrincipal, const ClonedMessageData& aData) {
   AUTO_PROFILER_LABEL_DYNAMIC_LOSSY_NSSTRING("BrowserParent::RecvAsyncMessage",
                                              OTHER, aMessage);
   MMPrinter::Print("BrowserParent::RecvAsyncMessage", aMessage, aData);
@@ -2077,7 +2079,7 @@ mozilla::ipc::IPCResult BrowserParent::RecvAsyncMessage(
   ipc::UnpackClonedMessageDataForParent(aData, data);
 
   CrossProcessCpowHolder cpows(Manager(), aCpows);
-  if (!ReceiveMessage(aMessage, false, &data, &cpows, nullptr)) {
+  if (!ReceiveMessage(aMessage, false, &data, &cpows, aPrincipal, nullptr)) {
     return IPC_FAIL_NO_REASON(this);
   }
   return IPC_OK();
@@ -3264,7 +3266,7 @@ mozilla::ipc::IPCResult BrowserParent::RecvDispatchFocusToTopLevelWindow() {
 
 bool BrowserParent::ReceiveMessage(const nsString& aMessage, bool aSync,
                                    StructuredCloneData* aData,
-                                   CpowHolder* aCpows,
+                                   CpowHolder* aCpows, nsIPrincipal* aPrincipal,
                                    nsTArray<StructuredCloneData>* aRetVal) {
   // If we're for an oop iframe, don't deliver messages to the wrong place.
   if (mBrowserBridgeParent) {
@@ -3277,7 +3279,7 @@ bool BrowserParent::ReceiveMessage(const nsString& aMessage, bool aSync,
         frameLoader->GetFrameMessageManager();
 
     manager->ReceiveMessage(mFrameElement, frameLoader, aMessage, aSync, aData,
-                            aCpows, aRetVal, IgnoreErrors());
+                            aCpows, aPrincipal, aRetVal, IgnoreErrors());
   }
   return true;
 }
diff --git a/dom/ipc/BrowserParent.h b/dom/ipc/BrowserParent.h
index e06ebc64d22f..96ff874dcbba 100644
--- a/dom/ipc/BrowserParent.h
+++ b/dom/ipc/BrowserParent.h
@@ -345,16 +345,17 @@ class BrowserParent final : public PBrowserParent,
 
   mozilla::ipc::IPCResult RecvSyncMessage(
       const nsString& aMessage, const ClonedMessageData& aData,
-      nsTArray<CpowEntry>&& aCpows,
+      nsTArray<CpowEntry>&& aCpows, nsIPrincipal* aPrincipal,
       nsTArray<ipc::StructuredCloneData>* aRetVal);
 
   mozilla::ipc::IPCResult RecvRpcMessage(
       const nsString& aMessage, const ClonedMessageData& aData,
-      nsTArray<CpowEntry>&& aCpows,
+      nsTArray<CpowEntry>&& aCpows, nsIPrincipal* aPrincipal,
       nsTArray<ipc::StructuredCloneData>* aRetVal);
 
   mozilla::ipc::IPCResult RecvAsyncMessage(const nsString& aMessage,
                                            nsTArray<CpowEntry>&& aCpows,
+                                           nsIPrincipal* aPrincipal,
                                            const ClonedMessageData& aData);
 
   mozilla::ipc::IPCResult RecvNotifyIMEFocus(
@@ -750,7 +751,7 @@ class BrowserParent final : public PBrowserParent,
 
   bool ReceiveMessage(
       const nsString& aMessage, bool aSync, ipc::StructuredCloneData* aData,
-      mozilla::jsipc::CpowHolder* aCpows,
+      mozilla::jsipc::CpowHolder* aCpows, nsIPrincipal* aPrincipal,
       nsTArray<ipc::StructuredCloneData>* aJSONRetVal = nullptr);
 
   mozilla::ipc::IPCResult RecvAsyncAuthPrompt(const nsCString& aUri,
diff --git a/dom/ipc/ContentChild.cpp b/dom/ipc/ContentChild.cpp
index 034089c58b21..3c0986316baf 100644
--- a/dom/ipc/ContentChild.cpp
+++ b/dom/ipc/ContentChild.cpp
@@ -955,6 +955,7 @@ nsresult ContentChild::ProvideWindowCommon(
     PopupIPCTabContext context;
     openerTabId = aTabOpener->GetTabId();
     context.opener() = openerTabId;
+    context.isMozBrowserElement() = aTabOpener->IsMozBrowserElement();
     ipcContext = MakeUnique<IPCTabContext>(context);
   } else {
     // It's possible to not have a BrowserChild opener in the case
@@ -992,11 +993,12 @@ nsresult ContentChild::ProvideWindowCommon(
   MutableTabContext newTabContext;
   if (aTabOpener) {
     newTabContext.SetTabContext(
-        aTabOpener->ChromeOuterWindowID(), aTabOpener->ShowFocusRings(),
-        browsingContext->OriginAttributesRef(), aTabOpener->PresentationURL(),
-        aTabOpener->MaxTouchPoints());
+        aTabOpener->IsMozBrowserElement(), aTabOpener->ChromeOuterWindowID(),
+        aTabOpener->ShowFocusRings(), browsingContext->OriginAttributesRef(),
+        aTabOpener->PresentationURL(), aTabOpener->MaxTouchPoints());
   } else {
     newTabContext.SetTabContext(
+        /* isMozBrowserElement */ false,
         /* chromeOuterWindowID */ 0,
         /* showFocusRings */ UIStateChangeType_NoChange,
         browsingContext->OriginAttributesRef(),
@@ -2354,7 +2356,7 @@ mozilla::ipc::IPCResult ContentChild::RecvLoadProcessScript(
 
 mozilla::ipc::IPCResult ContentChild::RecvAsyncMessage(
     const nsString& aMsg, nsTArray<CpowEntry>&& aCpows,
-    const ClonedMessageData& aData) {
+    const IPC::Principal& aPrincipal, const ClonedMessageData& aData) {
   AUTO_PROFILER_LABEL_DYNAMIC_LOSSY_NSSTRING("ContentChild::RecvAsyncMessage",
                                              OTHER, aMsg);
   MMPrinter::Print("ContentChild::RecvAsyncMessage", aMsg, aData);
@@ -2365,8 +2367,8 @@ mozilla::ipc::IPCResult ContentChild::RecvAsyncMessage(
   if (cpm) {
     StructuredCloneData data;
     ipc::UnpackClonedMessageDataForChild(aData, data);
-    cpm->ReceiveMessage(cpm, nullptr, aMsg, false, &data, &cpows, nullptr,
-                        IgnoreErrors());
+    cpm->ReceiveMessage(cpm, nullptr, aMsg, false, &data, &cpows, aPrincipal,
+                        nullptr, IgnoreErrors());
   }
   return IPC_OK();
 }
diff --git a/dom/ipc/ContentChild.h b/dom/ipc/ContentChild.h
index bf3faf33e347..9fb3e32b4ea1 100644
--- a/dom/ipc/ContentChild.h
+++ b/dom/ipc/ContentChild.h
@@ -343,6 +343,7 @@ class ContentChild final
 
   mozilla::ipc::IPCResult RecvAsyncMessage(const nsString& aMsg,
                                            nsTArray<CpowEntry>&& aCpows,
+                                           const IPC::Principal& aPrincipal,
                                            const ClonedMessageData& aData);
 
   mozilla::ipc::IPCResult RecvRegisterStringBundles(
diff --git a/dom/ipc/ContentParent.cpp b/dom/ipc/ContentParent.cpp
index 1647754c92a6..3272208eb917 100644
--- a/dom/ipc/ContentParent.cpp
+++ b/dom/ipc/ContentParent.cpp
@@ -1545,9 +1545,9 @@ void ContentParent::ShutDownMessageManager() {
     return;
   }
 
-  mMessageManager->ReceiveMessage(mMessageManager, nullptr,
-                                  CHILD_PROCESS_SHUTDOWN_MESSAGE, false,
-                                  nullptr, nullptr, nullptr, IgnoreErrors());
+  mMessageManager->ReceiveMessage(
+      mMessageManager, nullptr, CHILD_PROCESS_SHUTDOWN_MESSAGE, false, nullptr,
+      nullptr, nullptr, nullptr, IgnoreErrors());
 
   mMessageManager->SetOsPid(-1);
   mMessageManager->Disconnect();
@@ -3201,6 +3201,17 @@ bool ContentParent::CanOpenBrowser(const IPCTabContext& aContext) {
           "Got null opener from child; aborting AllocPBrowserParent.");
       return false;
     }
+
+    // Popup windows of isMozBrowserElement frames must be isMozBrowserElement
+    // if the parent isMozBrowserElement.  Allocating a !isMozBrowserElement
+    // frame with same app ID would allow the content to access data it's not
+    // supposed to.
+    if (!popupContext.isMozBrowserElement() && opener->IsMozBrowserElement()) {
+      ASSERT_UNLESS_FUZZING(
+          "Child trying to escalate privileges!  Aborting "
+          "AllocPBrowserParent.");
+      return false;
+    }
   }
 
   MaybeInvalidTabContext tc(aContext);
@@ -3897,7 +3908,8 @@ mozilla::ipc::IPCResult ContentParent::RecvNotificationEvent(
 
 mozilla::ipc::IPCResult ContentParent::RecvSyncMessage(
     const nsString& aMsg, const ClonedMessageData& aData,
-    nsTArray<CpowEntry>&& aCpows, nsTArray<StructuredCloneData>* aRetvals) {
+    nsTArray<CpowEntry>&& aCpows, const IPC::Principal& aPrincipal,
+    nsTArray<StructuredCloneData>* aRetvals) {
   AUTO_PROFILER_LABEL_DYNAMIC_LOSSY_NSSTRING("ContentParent::RecvSyncMessage",
                                              OTHER, aMsg);
   MMPrinter::Print("ContentParent::RecvSyncMessage", aMsg, aData);
@@ -3908,15 +3920,16 @@ mozilla::ipc::IPCResult ContentParent::RecvSyncMessage(
     ipc::StructuredCloneData data;
     ipc::UnpackClonedMessageDataForParent(aData, data);
 
-    ppm->ReceiveMessage(ppm, nullptr, aMsg, true, &data, &cpows, aRetvals,
-                        IgnoreErrors());
+    ppm->ReceiveMessage(ppm, nullptr, aMsg, true, &data, &cpows, aPrincipal,
+                        aRetvals, IgnoreErrors());
   }
   return IPC_OK();
 }
 
 mozilla::ipc::IPCResult ContentParent::RecvRpcMessage(
     const nsString& aMsg, const ClonedMessageData& aData,
-    nsTArray<CpowEntry>&& aCpows, nsTArray<StructuredCloneData>* aRetvals) {
+    nsTArray<CpowEntry>&& aCpows, const IPC::Principal& aPrincipal,
+    nsTArray<StructuredCloneData>* aRetvals) {
   AUTO_PROFILER_LABEL_DYNAMIC_LOSSY_NSSTRING("ContentParent::RecvRpcMessage",
                                              OTHER, aMsg);
   MMPrinter::Print("ContentParent::RecvRpcMessage", aMsg, aData);
@@ -3927,15 +3940,15 @@ mozilla::ipc::IPCResult ContentParent::RecvRpcMessage(
     ipc::StructuredCloneData data;
     ipc::UnpackClonedMessageDataForParent(aData, data);
 
-    ppm->ReceiveMessage(ppm, nullptr, aMsg, true, &data, &cpows, aRetvals,
-                        IgnoreErrors());
+    ppm->ReceiveMessage(ppm, nullptr, aMsg, true, &data, &cpows, aPrincipal,
+                        aRetvals, IgnoreErrors());
   }
   return IPC_OK();
 }
 
 mozilla::ipc::IPCResult ContentParent::RecvAsyncMessage(
     const nsString& aMsg, nsTArray<CpowEntry>&& aCpows,
-    const ClonedMessageData& aData) {
+    const IPC::Principal& aPrincipal, const ClonedMessageData& aData) {
   AUTO_PROFILER_LABEL_DYNAMIC_LOSSY_NSSTRING("ContentParent::RecvAsyncMessage",
                                              OTHER, aMsg);
   MMPrinter::Print("ContentParent::RecvAsyncMessage", aMsg, aData);
@@ -3946,8 +3959,8 @@ mozilla::ipc::IPCResult ContentParent::RecvAsyncMessage(
     ipc::StructuredCloneData data;
     ipc::UnpackClonedMessageDataForParent(aData, data);
 
-    ppm->ReceiveMessage(ppm, nullptr, aMsg, false, &data, &cpows, nullptr,
-                        IgnoreErrors());
+    ppm->ReceiveMessage(ppm, nullptr, aMsg, false, &data, &cpows, aPrincipal,
+                        nullptr, IgnoreErrors());
   }
   return IPC_OK();
 }
@@ -4144,7 +4157,8 @@ bool ContentParent::DoLoadMessageManagerScript(const nsAString& aURL,
 nsresult ContentParent::DoSendAsyncMessage(JSContext* aCx,
                                            const nsAString& aMessage,
                                            StructuredCloneData& aHelper,
-                                           JS::Handle<JSObject*> aCpows) {
+                                           JS::Handle<JSObject*> aCpows,
+                                           nsIPrincipal* aPrincipal) {
   ClonedMessageData data;
   if (!BuildClonedMessageDataForParent(this, aHelper, data)) {
     return NS_ERROR_DOM_DATA_CLONE_ERR;
@@ -4154,7 +4168,8 @@ nsresult ContentParent::DoSendAsyncMessage(JSContext* aCx,
   if (aCpows && (!mgr || !mgr->Wrap(aCx, aCpows, &cpows))) {
     return NS_ERROR_UNEXPECTED;
   }
-  if (!SendAsyncMessage(nsString(aMessage), cpows, data)) {
+  if (!SendAsyncMessage(nsString(aMessage), cpows, Principal(aPrincipal),
+                        data)) {
     return NS_ERROR_UNEXPECTED;
   }
   return NS_OK;
@@ -4665,6 +4680,10 @@ mozilla::ipc::IPCResult ContentParent::CommonCreateWindow(
   nsCOMPtr<nsIContent> frame;
   if (topParent) {
     frame = topParent->GetOwnerElement();
+
+    if (NS_WARN_IF(topParent->IsMozBrowserElement())) {
+      return IPC_FAIL(this, "aThisTab is not a MozBrowser");
+    }
   }
 
   nsCOMPtr<nsPIDOMWindowOuter> outerWin;
diff --git a/dom/ipc/ContentParent.h b/dom/ipc/ContentParent.h
index 76d70fcf7d1d..dc6a7c4c7464 100644
--- a/dom/ipc/ContentParent.h
+++ b/dom/ipc/ContentParent.h
@@ -351,7 +351,8 @@ class ContentParent final
 
   virtual nsresult DoSendAsyncMessage(JSContext* aCx, const nsAString& aMessage,
                                       StructuredCloneData& aData,
-                                      JS::Handle<JSObject*> aCpows) override;
+                                      JS::Handle<JSObject*> aCpows,
+                                      nsIPrincipal* aPrincipal) override;
 
   /** Notify that a tab is beginning its destruction sequence. */
   void NotifyTabDestroying();
@@ -1029,14 +1030,17 @@ class ContentParent final
 
   mozilla::ipc::IPCResult RecvSyncMessage(
       const nsString& aMsg, const ClonedMessageData& aData,
-      nsTArray<CpowEntry>&& aCpows, nsTArray<StructuredCloneData>* aRetvals);
+      nsTArray<CpowEntry>&& aCpows, const IPC::Principal& aPrincipal,
+      nsTArray<StructuredCloneData>* aRetvals);
 
   mozilla::ipc::IPCResult RecvRpcMessage(
       const nsString& aMsg, const ClonedMessageData& aData,
-      nsTArray<CpowEntry>&& aCpows, nsTArray<StructuredCloneData>* aRetvals);
+      nsTArray<CpowEntry>&& aCpows, const IPC::Principal& aPrincipal,
+      nsTArray<StructuredCloneData>* aRetvals);
 
   mozilla::ipc::IPCResult RecvAsyncMessage(const nsString& aMsg,
                                            nsTArray<CpowEntry>&& aCpows,
+                                           const IPC::Principal& aPrincipal,
                                            const ClonedMessageData& aData);
 
   // MOZ_CAN_RUN_SCRIPT_BOUNDARY because we don't have MOZ_CAN_RUN_SCRIPT bits
diff --git a/dom/ipc/PBrowser.ipdl b/dom/ipc/PBrowser.ipdl
index 2b968cef1193..dcfef2fac136 100644
--- a/dom/ipc/PBrowser.ipdl
+++ b/dom/ipc/PBrowser.ipdl
@@ -185,7 +185,7 @@ nested(upto inside_cpow) sync refcounted protocol PBrowser
 
 both:
     async AsyncMessage(nsString aMessage, CpowEntry[] aCpows,
-                       ClonedMessageData aData);
+                       nsIPrincipal aPrincipal, ClonedMessageData aData);
 
 parent:
 #ifdef ACCESSIBILITY
@@ -256,11 +256,11 @@ parent:
     async Event(RemoteDOMEvent aEvent);
 
     sync SyncMessage(nsString aMessage, ClonedMessageData aData,
-                     CpowEntry[] aCpows)
+                     CpowEntry[] aCpows, nsIPrincipal aPrincipal)
       returns (StructuredCloneData[] retval);
 
     nested(inside_sync) sync RpcMessage(nsString aMessage, ClonedMessageData aData,
-                                        CpowEntry[] aCpows)
+                                        CpowEntry[] aCpows, nsIPrincipal aPrincipal)
       returns (StructuredCloneData[] retval);
 
     /**
diff --git a/dom/ipc/PContent.ipdl b/dom/ipc/PContent.ipdl
index 0af6a2987e73..0efdd6658270 100644
--- a/dom/ipc/PContent.ipdl
+++ b/dom/ipc/PContent.ipdl
@@ -952,11 +952,11 @@ parent:
     sync GetGfxVars() returns (GfxVarUpdate[] vars);
 
     sync SyncMessage(nsString aMessage, ClonedMessageData aData,
-                     CpowEntry[] aCpows)
+                     CpowEntry[] aCpows, Principal aPrincipal)
       returns (StructuredCloneData[] retval);
 
     nested(inside_sync) sync RpcMessage(nsString aMessage, ClonedMessageData aData,
-                                        CpowEntry[] aCpows)
+                                        CpowEntry[] aCpows, Principal aPrincipal)
       returns (StructuredCloneData[] retval);
 
     async ShowAlert(nsIAlertNotification alert);
@@ -1568,7 +1568,7 @@ both:
                                            uint64_t aEpoch);
 
     async AsyncMessage(nsString aMessage, CpowEntry[] aCpows,
-                       ClonedMessageData aData);
+                       Principal aPrincipal, ClonedMessageData aData);
 
     /**
      * Notify `push-subscription-modified` observers in the parent and child.
diff --git a/dom/ipc/PTabContext.ipdlh b/dom/ipc/PTabContext.ipdlh
index 93cce54d2f61..a2ca31c1a9e4 100644
--- a/dom/ipc/PTabContext.ipdlh
+++ b/dom/ipc/PTabContext.ipdlh
@@ -17,9 +17,18 @@ namespace dom {
 
 // An IPCTabContext which corresponds to a PBrowser opened by a child when it
 // receives window.open().
+//
+// If isMozBrowserElement is false, this PopupIPCTabContext is either a
+// <xul:browser> or an app frame.  The frame's app-id and app-frame-owner-app-id
+// will be equal to the opener's values.
+//
+// It's an error to set isMozBrowserElement == false if opener is a mozbrowser
+// element.  Such a PopupIPCTabContext should be rejected by code which receives
+// it.
 struct PopupIPCTabContext
 {
   PBrowserOrId opener;
+  bool isMozBrowserElement;
   uint64_t chromeOuterWindowID;
 };
 
@@ -29,6 +38,10 @@ struct FrameIPCTabContext
   // The originAttributes dictionary.
   OriginAttributes originAttributes;
 
+  // Whether this is a mozbrowser frame.  <iframe mozbrowser mozapp> and
+  // <xul:browser> are not considered to be mozbrowser frames.
+  bool isMozBrowserElement;
+
   uint64_t chromeOuterWindowID;
 
   // The requested presentation URL.
diff --git a/dom/ipc/TabContext.cpp b/dom/ipc/TabContext.cpp
index 21658d132864..8078fb0a4c7b 100644
--- a/dom/ipc/TabContext.cpp
+++ b/dom/ipc/TabContext.cpp
@@ -19,11 +19,14 @@ namespace dom {
 
 TabContext::TabContext()
     : mInitialized(false),
+      mIsMozBrowserElement(false),
       mChromeOuterWindowID(0),
       mJSPluginID(-1),
       mShowFocusRings(UIStateChangeType_NoChange),
       mMaxTouchPoints(0) {}
 
+bool TabContext::IsMozBrowserElement() const { return mIsMozBrowserElement; }
+
 bool TabContext::IsJSPlugin() const { return mJSPluginID >= 0; }
 
 int32_t TabContext::JSPluginId() const { return mJSPluginID; }
@@ -54,13 +57,15 @@ bool TabContext::UpdateTabContextAfterSwap(const TabContext& aContext) {
   // This is only used after already initialized.
   MOZ_ASSERT(mInitialized);
 
-  // The only permissable changes are to mChromeOuterWindowID.  All other fields
-  // must match for the change to be accepted.
+  // The only permissable changes are to `mIsMozBrowserElement` and
+  // mChromeOuterWindowID.  All other fields must match for the change
+  // to be accepted.
   if (aContext.mOriginAttributes != mOriginAttributes) {
     return false;
   }
 
   mChromeOuterWindowID = aContext.mChromeOuterWindowID;
+  mIsMozBrowserElement = aContext.mIsMozBrowserElement;
   return true;
 }
 
@@ -74,7 +79,8 @@ const nsAString& TabContext::PresentationURL() const {
 
 UIStateChangeType TabContext::ShowFocusRings() const { return mShowFocusRings; }
 
-bool TabContext::SetTabContext(uint64_t aChromeOuterWindowID,
+bool TabContext::SetTabContext(bool aIsMozBrowserElement,
+                               uint64_t aChromeOuterWindowID,
                                UIStateChangeType aShowFocusRings,
                                const OriginAttributes& aOriginAttributes,
                                const nsAString& aPresentationURL,
@@ -82,6 +88,7 @@ bool TabContext::SetTabContext(uint64_t aChromeOuterWindowID,
   NS_ENSURE_FALSE(mInitialized, false);
 
   mInitialized = true;
+  mIsMozBrowserElement = aIsMozBrowserElement;
   mChromeOuterWindowID = aChromeOuterWindowID;
   mOriginAttributes = aOriginAttributes;
   mPresentationURL = aPresentationURL;
@@ -103,13 +110,14 @@ IPCTabContext TabContext::AsIPCTabContext() const {
     return IPCTabContext(JSPluginFrameIPCTabContext(mJSPluginID));
   }
 
-  return IPCTabContext(
-      FrameIPCTabContext(mOriginAttributes, mChromeOuterWindowID,
-                         mPresentationURL, mShowFocusRings, mMaxTouchPoints));
+  return IPCTabContext(FrameIPCTabContext(
+      mOriginAttributes, mIsMozBrowserElement, mChromeOuterWindowID,
+      mPresentationURL, mShowFocusRings, mMaxTouchPoints));
 }
 
 MaybeInvalidTabContext::MaybeInvalidTabContext(const IPCTabContext& aParams)
     : mInvalidReason(nullptr) {
+  bool isMozBrowserElement = false;
   uint64_t chromeOuterWindowID = 0;
   int32_t jsPluginId = -1;
   OriginAttributes originAttributes;
@@ -131,6 +139,17 @@ MaybeInvalidTabContext::MaybeInvalidTabContext(const IPCTabContext& aParams)
               "open a null tab.";
           return;
         }
+        if (context->IsMozBrowserElement() &&
+            !ipcContext.isMozBrowserElement()) {
+          // If the BrowserParent corresponds to a browser element, then it can
+          // only open other browser elements, for security reasons.  We should
+          // have checked this before calling the TabContext constructor, so
+          // this is a fatal error.
+          mInvalidReason =
+              "Child is-browser process tried to "
+              "open a non-browser tab.";
+          return;
+        }
       } else if (ipcContext.opener().type() == PBrowserOrId::TPBrowserChild) {
         context =
             static_cast<BrowserChild*>(ipcContext.opener().get_PBrowserChild());
@@ -148,6 +167,14 @@ MaybeInvalidTabContext::MaybeInvalidTabContext(const IPCTabContext& aParams)
         return;
       }
 
+      // Browser elements can't nest other browser elements.  So if
+      // our opener is browser element, we must be a new DOM window
+      // opened by it.  In that case we inherit our containing app ID
+      // (if any).
+      //
+      // Otherwise, we're a new app window and we inherit from our
+      // opener app.
+      isMozBrowserElement = ipcContext.isMozBrowserElement();
       originAttributes = context->mOriginAttributes;
       chromeOuterWindowID = ipcContext.chromeOuterWindowID();
       break;
@@ -162,6 +189,7 @@ MaybeInvalidTabContext::MaybeInvalidTabContext(const IPCTabContext& aParams)
     case IPCTabContext::TFrameIPCTabContext: {
       const FrameIPCTabContext& ipcContext = aParams.get_FrameIPCTabContext();
 
+      isMozBrowserElement = ipcContext.isMozBrowserElement();
       chromeOuterWindowID = ipcContext.chromeOuterWindowID();
       presentationURL = ipcContext.presentationURL();
       showFocusRings = ipcContext.showFocusRings();
@@ -190,9 +218,9 @@ MaybeInvalidTabContext::MaybeInvalidTabContext(const IPCTabContext& aParams)
   if (jsPluginId >= 0) {
     rv = mTabContext.SetTabContextForJSPluginFrame(jsPluginId);
   } else {
-    rv = mTabContext.SetTabContext(chromeOuterWindowID, showFocusRings,
-                                   originAttributes, presentationURL,
-                                   maxTouchPoints);
+    rv = mTabContext.SetTabContext(isMozBrowserElement, chromeOuterWindowID,
+                                   showFocusRings, originAttributes,
+                                   presentationURL, maxTouchPoints);
   }
   if (!rv) {
     mInvalidReason = "Couldn't initialize TabContext.";
diff --git a/dom/ipc/TabContext.h b/dom/ipc/TabContext.h
index 16e469d9de16..32db524acb24 100644
--- a/dom/ipc/TabContext.h
+++ b/dom/ipc/TabContext.h
@@ -18,7 +18,7 @@ namespace dom {
 class IPCTabContext;
 
 /**
- * TabContext encapsulates information about an iframe.
+ * TabContext encapsulates information about an iframe that may be a mozbrowser.
  *
  * BrowserParent and BrowserChild both inherit from TabContext, and you can also
  * have standalone TabContext objects.
@@ -39,6 +39,13 @@ class TabContext {
    */
   IPCTabContext AsIPCTabContext() const;
 
+  /**
+   * Does this TabContext correspond to a mozbrowser?
+   *
+   * <iframe mozbrowser> is a mozbrowser element, but <xul:browser> is not.
+   */
+  bool IsMozBrowserElement() const;
+
   bool IsJSPlugin() const;
   int32_t JSPluginId() const;
 
@@ -88,7 +95,7 @@ class TabContext {
    */
   void SetFirstPartyDomainAttributes(const nsAString& aFirstPartyDomain);
 
-  bool SetTabContext(uint64_t aChromeOuterWindowID,
+  bool SetTabContext(bool aIsMozBrowserElement, uint64_t aChromeOuterWindowID,
                      UIStateChangeType aShowFocusRings,
                      const OriginAttributes& aOriginAttributes,
                      const nsAString& aPresentationURL,
@@ -99,7 +106,7 @@ class TabContext {
    * case triggered by nsFrameLoader::SwapWithOtherRemoteLoader which may have
    * caused the owner content to change.
    *
-   * This special case only allows the field `mChromeOuterWindowID` to be
+   * This special case only allows the field `mIsMozBrowserElement` to be
    * changed.  If any other fields have changed, the update is ignored and
    * returns false.
    */
@@ -125,6 +132,14 @@ class TabContext {
    */
   bool mInitialized;
 
+  /**
+   * Whether this TabContext corresponds to a mozbrowser.
+   *
+   * <iframe mozbrowser> and <xul:browser> are not considered to be
+   * mozbrowser elements.
+   */
+  bool mIsMozBrowserElement;
+
   /**
    * The outerWindowID of the window hosting the remote frameloader.
    */
@@ -164,14 +179,14 @@ class MutableTabContext : public TabContext {
     return TabContext::SetTabContext(aContext);
   }
 
-  bool SetTabContext(uint64_t aChromeOuterWindowID,
+  bool SetTabContext(bool aIsMozBrowserElement, uint64_t aChromeOuterWindowID,
                      UIStateChangeType aShowFocusRings,
                      const OriginAttributes& aOriginAttributes,
                      const nsAString& aPresentationURL,
                      uint32_t aMaxTouchPoints) {
-    return TabContext::SetTabContext(aChromeOuterWindowID, aShowFocusRings,
-                                     aOriginAttributes, aPresentationURL,
-                                     aMaxTouchPoints);
+    return TabContext::SetTabContext(aIsMozBrowserElement, aChromeOuterWindowID,
+                                     aShowFocusRings, aOriginAttributes,
+                                     aPresentationURL, aMaxTouchPoints);
   }
 
   bool SetTabContextForJSPluginFrame(uint32_t aJSPluginID) {
diff --git a/dom/ipc/tests/browser.ini b/dom/ipc/tests/browser.ini
index cc54c21dc0ca..e8198cd43a3e 100644
--- a/dom/ipc/tests/browser.ini
+++ b/dom/ipc/tests/browser.ini
@@ -6,8 +6,6 @@ support-files =
   ../../media/test/short.mp4
   ../../media/test/owl.mp3
 
-[browser_CrashService_crash.js]
-skip-if = !crashreporter
 [browser_ProcessPriorityManager.js]
 skip-if = os != "win" # The Process Priority Manager is only enabled for Windows so far. Bug 1522879.
 [browser_crash_oopiframe.js]
diff --git a/dom/ipc/tests/browser_CrashService_crash.js b/dom/ipc/tests/browser_CrashService_crash.js
deleted file mode 100644
index 17fa6d2d3861..000000000000
--- a/dom/ipc/tests/browser_CrashService_crash.js
+++ /dev/null
@@ -1,71 +0,0 @@
-/* Any copyright is dedicated to the Public Domain.
-   http://creativecommons.org/publicdomain/zero/1.0/ */
-"use strict";
-
-// Ensures that content crashes are reported to the crash service
-// (nsICrashService and CrashManager.jsm).
-
-/* eslint-disable mozilla/no-arbitrary-setTimeout */
-SimpleTest.requestFlakyTimeout("untriaged");
-
-add_task(async function() {
-  let tab = await BrowserTestUtils.openNewForegroundTab({
-    gBrowser,
-    forceNewProcess: true,
-  });
-
-  SimpleTest.expectChildProcessCrash();
-
-  let crashMan = Services.crashmanager;
-
-  // First, clear the crash record store.
-  info("Waiting for pruneOldCrashes");
-  var future = new Date(Date.now() + 1000 * 60 * 60 * 24);
-  await crashMan.pruneOldCrashes(future);
-
-  var crashDateMS = Date.now();
-
-  let crashPromise = BrowserTestUtils.crashFrame(tab.linkedBrowser);
-
-  // Finally, poll for the new crash record.
-  await new Promise((resolve, reject) => {
-    function tryGetCrash() {
-      info("Waiting for getCrashes");
-      crashMan.getCrashes().then(
-        function(crashes) {
-          if (crashes.length) {
-            is(crashes.length, 1, "There should be only one record");
-            var crash = crashes[0];
-            ok(
-              crash.isOfType(
-                crashMan.PROCESS_TYPE_CONTENT,
-                crashMan.CRASH_TYPE_CRASH
-              ),
-              "Record should be a content crash"
-            );
-            ok(!!crash.id, "Record should have an ID");
-            ok(!!crash.crashDate, "Record should have a crash date");
-            var dateMS = crash.crashDate.valueOf();
-            var twoMin = 1000 * 60 * 2;
-            ok(
-              crashDateMS - twoMin <= dateMS && dateMS <= crashDateMS + twoMin,
-              `Record's crash date should be nowish: ` +
-                `now=${crashDateMS} recordDate=${dateMS}`
-            );
-            resolve();
-          } else {
-            setTimeout(tryGetCrash, 1000);
-          }
-        },
-        function(err) {
-          reject(err);
-        }
-      );
-    }
-    setTimeout(tryGetCrash, 1000);
-  });
-
-  await crashPromise;
-
-  await BrowserTestUtils.removeTab(tab);
-});
diff --git a/dom/ipc/tests/browser_domainPolicy.js b/dom/ipc/tests/browser_domainPolicy.js
index cec360f2e14f..a90f3e9084fe 100644
--- a/dom/ipc/tests/browser_domainPolicy.js
+++ b/dom/ipc/tests/browser_domainPolicy.js
@@ -57,7 +57,11 @@ function deactivateDomainPolicy() {
 
 add_task(async function setup() {
   await SpecialPowers.pushPrefEnv({
-    set: [["browser.pagethumbnails.capturing_disabled", false]],
+    set: [
+      ["dom.ipc.browser_frames.oop_by_default", false],
+      ["browser.pagethumbnails.capturing_disabled", false],
+      ["dom.mozBrowserFramesEnabled", false],
+    ],
   });
 
   registerCleanupFunction(() => {
diff --git a/dom/ipc/tests/file_bug1086684.html b/dom/ipc/tests/file_bug1086684.html
new file mode 100644
index 000000000000..95db6f387dea
--- /dev/null
+++ b/dom/ipc/tests/file_bug1086684.html
@@ -0,0 +1,16 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=1086684
+-->
+<head>
+  <title>Test for Bug 1086684</title>
+  <meta charset="UTF-8">
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1086684">Mozilla Bug 1086684</a>
+<div id="content">
+    <input type="file" id="f">
+</div>
+</body>
+</html>
diff --git a/dom/ipc/tests/mochitest.ini b/dom/ipc/tests/mochitest.ini
index 37cdd9d48eff..5bd0a666e1b6 100644
--- a/dom/ipc/tests/mochitest.ini
+++ b/dom/ipc/tests/mochitest.ini
@@ -1,5 +1,21 @@
 [DEFAULT]
+support-files =
+  file_bug1086684.html
 
+[test_blob_sliced_from_child_process.html]
+# This test is only supposed to run in the main process.
+skip-if = e10s
+[test_blob_sliced_from_parent_process.html]
+# This test is only supposed to run in the main process.
+skip-if = e10s
+[test_bug1086684.html]
+# This test is only supposed to run in the main process
+skip-if = e10s
+[test_cpow_cookies.html]
+[test_child_docshell.html]
+skip-if = toolkit == 'cocoa' # cocoa: disabled due to hangs, see changeset 6852e7c47edf
+[test_CrashService_crash.html]
+skip-if = !(crashreporter && !e10s && (toolkit == 'gtk' || toolkit == 'cocoa' || toolkit == 'windows'))
 [test_temporaryfile_stream.html]
 skip-if = !e10s || toolkit == 'android' || (os == "win" && processor == "aarch64") # Bug 1525959, aarch64 due to 1531150
 support-files =
diff --git a/dom/ipc/tests/test_CrashService_crash.html b/dom/ipc/tests/test_CrashService_crash.html
new file mode 100644
index 000000000000..44756b3e820f
--- /dev/null
+++ b/dom/ipc/tests/test_CrashService_crash.html
@@ -0,0 +1,90 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+Ensures that content crashes are reported to the crash service
+(nsICrashService and CrashManager.jsm).
+-->
+<head>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+<script type="application/javascript">
+"use strict";
+
+SimpleTest.waitForExplicitFinish();
+SimpleTest.requestFlakyTimeout("untriaged");
+SpecialPowers.addPermission("browser", true, document);
+SpecialPowers.pushPrefEnv({"set": [
+  ["dom.mozBrowserFramesEnabled", true],
+  ["network.disable.ipc.security", true],
+  ["dom.ipc.tabs.disabled", false],
+]}, function() {
+  var iframe =  document.createElementNS("http://www.w3.org/1999/xhtml", "iframe");
+  iframe.setAttribute("remote", "true");
+  SpecialPowers.wrap(iframe).mozbrowser = true;
+  document.documentElement.appendChild(iframe);
+
+  SimpleTest.expectChildProcessCrash();
+
+  var crashMan =
+    SpecialPowers.Cu.import("resource://gre/modules/Services.jsm").
+    Services.crashmanager;
+
+  // First, clear the crash record store.
+  info("Waiting for pruneOldCrashes");
+  var future = new Date(Date.now() + 1000 * 60 * 60 * 24);
+  crashMan.pruneOldCrashes(future).then(function() {
+    var crashDateMS = Date.now();
+
+    // Inject a frame script that crashes the content process.
+    var mm = SpecialPowers.getBrowserFrameMessageManager(iframe);
+    mm.loadFrameScript("data:,new " + function ContentScriptScope() {
+      const {ctypes} = ChromeUtils.import("resource://gre/modules/ctypes.jsm");
+      let crash = function() {
+        let zero = new ctypes.intptr_t(8);
+        let badptr = ctypes.cast(zero, ctypes.PointerType(ctypes.int32_t));
+        badptr.contents;
+      };
+      privateNoteIntentionalCrash();
+      crash();
+    }, false);
+
+    // Finally, poll for the new crash record.
+    function tryGetCrash() {
+      info("Waiting for getCrashes");
+      crashMan.getCrashes().then(SpecialPowers.wrapCallback(function(crashes) {
+        if (crashes.length) {
+          is(crashes.length, 1, "There should be only one record");
+          var crash = crashes[0];
+          ok(crash.isOfType(crashMan.PROCESS_TYPE_CONTENT,
+                            crashMan.CRASH_TYPE_CRASH),
+             "Record should be a content crash");
+          ok(!!crash.id, "Record should have an ID");
+          ok(!!crash.crashDate, "Record should have a crash date");
+          var dateMS = crash.crashDate.valueOf();
+          var twoMin = 1000 * 60 * 2;
+          ok(crashDateMS - twoMin <= dateMS &&
+             dateMS <= crashDateMS + twoMin,
+             "Record's crash date should be nowish: " +
+             "now=" + crashDateMS + " recordDate=" + dateMS);
+          SimpleTest.finish();
+        } else {
+          setTimeout(tryGetCrash, 1000);
+        }
+      }), function(err) {
+        ok(false, "Error getting crashes: " + err);
+        SimpleTest.finish();
+      });
+    }
+    setTimeout(tryGetCrash, 1000);
+  }, function() {
+    ok(false, "pruneOldCrashes error");
+    SimpleTest.finish();
+  });
+});
+
+</script>
+</body>
+</html>
diff --git a/dom/ipc/tests/test_blob_sliced_from_child_process.html b/dom/ipc/tests/test_blob_sliced_from_child_process.html
new file mode 100644
index 000000000000..b4a6998000af
--- /dev/null
+++ b/dom/ipc/tests/test_blob_sliced_from_child_process.html
@@ -0,0 +1,180 @@
+<!DOCTYPE html>
+<html>
+  <head>
+    <title>Test for slicing blobs that originated in a child process</title>
+    <script src="/tests/SimpleTest/SimpleTest.js">
+    </script>
+    <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+  </head>
+  <body onload="setup();">
+    <script type="application/javascript">
+"use strict";
+/* eslint-env mozilla/frame-script */
+
+function childFrameScript() {
+  "use strict";
+
+  const messageName = "test:blob-slice-test";
+  const blobData = ["So", " ", "many", " ", "blobs!"];
+  const blobType = "text/plain";
+
+  let blob = new Blob(blobData, { type: blobType });
+
+  let firstSliceStart = blobData[0].length + blobData[1].length;
+  let firstSliceEnd = firstSliceStart + blobData[2].length;
+
+  let slice = blob.slice(firstSliceStart, firstSliceEnd, blobType);
+
+  let secondSliceStart = blobData[2].indexOf("a");
+  let secondSliceEnd = secondSliceStart + 2;
+
+  slice = slice.slice(secondSliceStart, secondSliceEnd, blobType);
+
+  sendAsyncMessage(messageName, { blob });
+  sendAsyncMessage(messageName, { slice });
+}
+
+function parentFrameScript(mm) {
+  const messageName = "test:blob-slice-test";
+  const blobData = ["So", " ", "many", " ", "blobs!"];
+  const blobText = blobData.join("");
+  const blobType = "text/plain";
+
+  const sliceText = "an";
+
+  let receivedBlob = false;
+  let receivedSlice = false;
+
+  let finishedTestingBlob = false;
+  let finishedTestingSlice = false;
+
+  mm.addMessageListener(messageName, SpecialPowers.wrapCallback(function(message) {
+    if ("blob" in message.data) {
+      is(receivedBlob, false, "Have not yet received Blob");
+      is(receivedSlice, false, "Have not yet received Slice");
+      is(finishedTestingBlob, false, "Have not yet finished testing Blob");
+      is(finishedTestingSlice, false, "Have not yet finished testing Slice");
+
+      receivedBlob = true;
+
+      let blob = message.data.blob;
+
+      ok(SpecialPowers.call_Instanceof(blob, Blob), "Received a Blob");
+      is(blob.size, blobText.length, "Blob has correct size");
+      is(blob.type, blobType, "Blob has correct type");
+
+      let slice = blob.slice(blobText.length -
+                                blobData[blobData.length - 1].length,
+                              blob.size,
+                              blobType);
+
+      ok(SpecialPowers.call_Instanceof(slice, Blob), "Slice returned a Blob");
+      is(slice.size,
+          blobData[blobData.length - 1].length,
+          "Slice has correct size");
+      is(slice.type, blobType, "Slice has correct type");
+
+      let reader = new FileReader();
+      reader.onload = function() {
+        is(reader.result,
+            blobData[blobData.length - 1],
+            "Slice has correct data");
+
+        finishedTestingBlob = true;
+
+        if (finishedTestingSlice) {
+          SimpleTest.finish();
+        }
+      };
+      SpecialPowers.wrap(reader).readAsText(slice);
+
+      return;
+    }
+
+    if ("slice" in message.data) {
+      is(receivedBlob, true, "Already received Blob");
+      is(receivedSlice, false, "Have not yet received Slice");
+      is(finishedTestingSlice, false, "Have not yet finished testing Slice");
+
+      receivedSlice = true;
+
+      let slice = message.data.slice;
+
+      ok(SpecialPowers.call_Instanceof(slice, Blob), "Received a Blob for slice");
+      is(slice.size, sliceText.length, "Slice has correct size");
+      is(slice.type, blobType, "Slice has correct type");
+
+      let reader = new FileReader();
+      reader.onload = function() {
+        is(reader.result, sliceText, "Slice has correct data");
+
+        let slice2 = slice.slice(1, 2, blobType);
+
+        ok(SpecialPowers.call_Instanceof(slice2, Blob), "Slice returned a Blob");
+        is(slice2.size, 1, "Slice has correct size");
+        is(slice2.type, blobType, "Slice has correct type");
+
+        let reader2 = new FileReader();
+        reader2.onload = function() {
+          is(reader2.result, sliceText[1], "Slice has correct data");
+
+          finishedTestingSlice = true;
+
+          if (finishedTestingBlob) {
+            SimpleTest.finish();
+          }
+        };
+        SpecialPowers.wrap(reader2).readAsText(slice2);
+      };
+      SpecialPowers.wrap(reader).readAsText(slice);
+
+      return;
+    }
+
+    ok(false, "Received a bad message: " + JSON.stringify(message.data));
+  }));
+
+  mm.loadFrameScript("data:,(" + childFrameScript.toString() + ")();",
+                      false);
+}
+
+function setup() {
+  info("Got load event");
+
+  SpecialPowers.pushPrefEnv(
+    { set: [ ["dom.ipc.browser_frames.oop_by_default", true],
+              ["dom.mozBrowserFramesEnabled", true],
+              ["network.disable.ipc.security", true],
+              ["browser.pagethumbnails.capturing_disabled", true] ] },
+    function() {
+      info("Prefs set");
+
+      SpecialPowers.pushPermissions(
+        [ { type: "browser", allow: true, context: document } ],
+        function() {
+          info("Permissions set");
+
+          let iframe = document.createElement("iframe");
+          SpecialPowers.wrap(iframe).mozbrowser = true;
+          iframe.id = "iframe";
+          iframe.src =
+            "data:text/html,<!DOCTYPE HTML><html><body></body></html>";
+
+          iframe.addEventListener("mozbrowserloadend", function() {
+            info("Starting tests");
+
+            let mm = SpecialPowers.getBrowserFrameMessageManager(iframe);
+            parentFrameScript(mm);
+          });
+
+          document.body.appendChild(iframe);
+        }
+      );
+    }
+  );
+}
+
+SimpleTest.waitForExplicitFinish();
+  </script>
+  </body>
+</html>
diff --git a/dom/ipc/tests/test_blob_sliced_from_child_process.js b/dom/ipc/tests/test_blob_sliced_from_child_process.js
deleted file mode 100644
index 16d5d5e13640..000000000000
--- a/dom/ipc/tests/test_blob_sliced_from_child_process.js
+++ /dev/null
@@ -1,138 +0,0 @@
-"use strict";
-/* eslint-env mozilla/frame-script */
-
-const { ExtensionTestUtils } = ChromeUtils.import(
-  "resource://testing-common/ExtensionXPCShellUtils.jsm"
-);
-
-ExtensionTestUtils.init(this);
-
-function childFrameScript() {
-  "use strict";
-
-  const messageName = "test:blob-slice-test";
-  const blobData = ["So", " ", "many", " ", "blobs!"];
-  const blobType = "text/plain";
-
-  let blob = new Blob(blobData, { type: blobType });
-
-  let firstSliceStart = blobData[0].length + blobData[1].length;
-  let firstSliceEnd = firstSliceStart + blobData[2].length;
-
-  let slice = blob.slice(firstSliceStart, firstSliceEnd, blobType);
-
-  let secondSliceStart = blobData[2].indexOf("a");
-  let secondSliceEnd = secondSliceStart + 2;
-
-  slice = slice.slice(secondSliceStart, secondSliceEnd, blobType);
-
-  sendAsyncMessage(messageName, { blob });
-  sendAsyncMessage(messageName, { slice });
-}
-
-add_task(async function test() {
-  let page = await ExtensionTestUtils.loadContentPage(
-    "data:text/html,<!DOCTYPE HTML><html><body></body></html>",
-    {
-      remote: true,
-    }
-  );
-
-  page.loadFrameScript(childFrameScript);
-
-  const messageName = "test:blob-slice-test";
-  const blobData = ["So", " ", "many", " ", "blobs!"];
-  const blobText = blobData.join("");
-  const blobType = "text/plain";
-
-  const sliceText = "an";
-
-  let receivedBlob = false;
-  let receivedSlice = false;
-
-  let resolveBlob, resolveSlice;
-  let blobPromise = new Promise(resolve => {
-    resolveBlob = resolve;
-  });
-  let slicePromise = new Promise(resolve => {
-    resolveSlice = resolve;
-  });
-
-  let mm = page.browser.messageManager;
-  mm.addMessageListener(messageName, function(message) {
-    if ("blob" in message.data) {
-      equal(receivedBlob, false, "Have not yet received Blob");
-      equal(receivedSlice, false, "Have not yet received Slice");
-
-      receivedBlob = true;
-
-      let blob = message.data.blob;
-
-      ok(Blob.isInstance(blob), "Received a Blob");
-      equal(blob.size, blobText.length, "Blob has correct size");
-      equal(blob.type, blobType, "Blob has correct type");
-
-      let slice = blob.slice(
-        blobText.length - blobData[blobData.length - 1].length,
-        blob.size,
-        blobType
-      );
-
-      ok(Blob.isInstance(slice), "Slice returned a Blob");
-      equal(
-        slice.size,
-        blobData[blobData.length - 1].length,
-        "Slice has correct size"
-      );
-      equal(slice.type, blobType, "Slice has correct type");
-
-      let reader = new FileReader();
-      reader.onload = function() {
-        equal(
-          reader.result,
-          blobData[blobData.length - 1],
-          "Slice has correct data"
-        );
-
-        resolveBlob();
-      };
-      reader.readAsText(slice);
-    } else if ("slice" in message.data) {
-      equal(receivedBlob, true, "Already received Blob");
-      equal(receivedSlice, false, "Have not yet received Slice");
-
-      receivedSlice = true;
-
-      let slice = message.data.slice;
-
-      ok(Blob.isInstance(slice), "Received a Blob for slice");
-      equal(slice.size, sliceText.length, "Slice has correct size");
-      equal(slice.type, blobType, "Slice has correct type");
-
-      let reader = new FileReader();
-      reader.onload = function() {
-        equal(reader.result, sliceText, "Slice has correct data");
-
-        let slice2 = slice.slice(1, 2, blobType);
-
-        ok(Blob.isInstance(slice2), "Slice returned a Blob");
-        equal(slice2.size, 1, "Slice has correct size");
-        equal(slice2.type, blobType, "Slice has correct type");
-
-        let reader2 = new FileReader();
-        reader2.onload = function() {
-          equal(reader2.result, sliceText[1], "Slice has correct data");
-
-          resolveSlice();
-        };
-        reader2.readAsText(slice2);
-      };
-      reader.readAsText(slice);
-    } else {
-      ok(false, "Received a bad message: " + JSON.stringify(message.data));
-    }
-  });
-
-  await blobPromise;
-  await slicePromise;
-});
diff --git a/dom/ipc/tests/test_blob_sliced_from_parent_process.html b/dom/ipc/tests/test_blob_sliced_from_parent_process.html
new file mode 100644
index 000000000000..0b587ad3cfeb
--- /dev/null
+++ b/dom/ipc/tests/test_blob_sliced_from_parent_process.html
@@ -0,0 +1,207 @@
+<!DOCTYPE html>
+<html>
+  <head>
+    <title>Test for slicing blobs that originated in a parent process</title>
+    <script src="/tests/SimpleTest/SimpleTest.js">
+    </script>
+    <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+  </head>
+  <body onload="setup();">
+    <script type="application/javascript">
+"use strict";
+/* eslint-env mozilla/frame-script */
+
+function childFrameScript() {
+  "use strict";
+
+  const messageName = "test:blob-slice-test";
+  const blobData = ["So", " ", "many", " ", "blobs!"];
+  const blobText = blobData.join("");
+  const blobType = "text/plain";
+
+  const sliceText = "an";
+
+  function info(msg) {
+    sendAsyncMessage(messageName, { op: "info", msg });
+  }
+
+  function ok(condition, name, diag) {
+    sendAsyncMessage(messageName,
+                     { op: "ok",
+                       condition,
+                       name,
+                       diag });
+  }
+
+  function is(a, b, name) {
+    let pass = a == b;
+    let diag = pass ? "" : "got " + a + ", expected " + b;
+    ok(pass, name, diag);
+  }
+
+  function finish(result) {
+    sendAsyncMessage(messageName, { op: "done", result });
+  }
+
+  function grabAndContinue(arg) {
+    testGenerator.next(arg);
+  }
+
+  function* testSteps() {
+    addMessageListener(messageName, grabAndContinue);
+    let message = yield undefined;
+
+    let blob = message.data;
+
+    ok(Blob.isInstance(blob), "Received a Blob");
+    is(blob.size, blobText.length, "Blob has correct length");
+    is(blob.type, blobType, "Blob has correct type");
+
+    info("Reading blob");
+
+    let reader = new FileReader();
+    reader.addEventListener("load", grabAndContinue);
+    reader.readAsText(blob);
+
+    yield undefined;
+
+    is(reader.result, blobText, "Blob has correct data");
+
+    let firstSliceStart = blobData[0].length + blobData[1].length;
+    let firstSliceEnd = firstSliceStart + blobData[2].length;
+
+    let slice = blob.slice(firstSliceStart, firstSliceEnd, blobType);
+
+    ok(Blob.isInstance(slice), "Slice returned a Blob");
+    is(slice.size, blobData[2].length, "Slice has correct length");
+    is(slice.type, blobType, "Slice has correct type");
+
+    info("Reading slice");
+
+    reader = new FileReader();
+    reader.addEventListener("load", grabAndContinue);
+    reader.readAsText(slice);
+
+    yield undefined;
+
+    is(reader.result, blobData[2], "Slice has correct data");
+
+    let secondSliceStart = blobData[2].indexOf("a");
+    let secondSliceEnd = secondSliceStart + sliceText.length;
+
+    slice = slice.slice(secondSliceStart, secondSliceEnd, blobType);
+
+    ok(Blob.isInstance(slice), "Second slice returned a Blob");
+    is(slice.size, sliceText.length, "Second slice has correct length");
+    is(slice.type, blobType, "Second slice has correct type");
+
+    info("Sending second slice");
+    finish(slice);
+  }
+
+  let testGenerator = testSteps();
+  testGenerator.next();
+}
+
+function parentFrameScript(mm) {
+  const messageName = "test:blob-slice-test";
+  const blobData = ["So", " ", "many", " ", "blobs!"];
+  const blobType = "text/plain";
+
+  const sliceText = "an";
+
+  function grabAndContinue(arg) {
+    testGenerator.next(arg);
+  }
+
+  function* testSteps() {
+    let slice = yield undefined;
+
+    ok(SpecialPowers.call_Instanceof(slice, Blob), "Received a Blob");
+    is(slice.size, sliceText.length, "Slice has correct size");
+    is(slice.type, blobType, "Slice has correct type");
+
+    let reader = new FileReader();
+    reader.onload = grabAndContinue;
+    SpecialPowers.wrap(reader).readAsText(slice);
+    yield undefined;
+
+    is(reader.result, sliceText, "Slice has correct data");
+    SimpleTest.finish();
+  }
+
+  let testGenerator = testSteps();
+  testGenerator.next();
+
+  mm.addMessageListener(messageName, SpecialPowers.wrapCallback(function(message) {
+    let data = message.data;
+    switch (data.op) {
+      case "info": {
+        info(data.msg);
+        break;
+      }
+
+      case "ok": {
+        ok(data.condition, data.name + " - " + data.diag);
+        break;
+      }
+
+      case "done": {
+        testGenerator.next(data.result);
+        break;
+      }
+
+      default: {
+        ok(false, "Unknown op: " + data.op);
+        SimpleTest.finish();
+      }
+    }
+  }));
+
+  mm.loadFrameScript("data:,(" + childFrameScript.toString() + ")();",
+                      false);
+
+  let blob = new Blob(blobData, { type: blobType });
+  mm.sendAsyncMessage(messageName, blob);
+}
+
+function setup() {
+  info("Got load event");
+
+  SpecialPowers.pushPrefEnv(
+    { set: [ ["dom.ipc.browser_frames.oop_by_default", true],
+             ["dom.mozBrowserFramesEnabled", true],
+             ["network.disable.ipc.security", true],
+             ["browser.pagethumbnails.capturing_disabled", true] ] },
+    function() {
+      info("Prefs set");
+
+      SpecialPowers.pushPermissions(
+        [ { type: "browser", allow: true, context: document } ],
+        function() {
+          info("Permissions set");
+
+          let iframe = document.createElement("iframe");
+          SpecialPowers.wrap(iframe).mozbrowser = true;
+          iframe.id = "iframe";
+          iframe.src =
+            "data:text/html,<!DOCTYPE HTML><html><body></body></html>";
+
+          iframe.addEventListener("mozbrowserloadend", function() {
+            info("Starting tests");
+
+            let mm = SpecialPowers.getBrowserFrameMessageManager(iframe);
+            parentFrameScript(mm);
+          });
+
+          document.body.appendChild(iframe);
+        }
+      );
+    }
+  );
+}
+
+SimpleTest.waitForExplicitFinish();
+    </script>
+  </body>
+</html>
diff --git a/dom/ipc/tests/test_blob_sliced_from_parent_process.js b/dom/ipc/tests/test_blob_sliced_from_parent_process.js
deleted file mode 100644
index a166b9e290fa..000000000000
--- a/dom/ipc/tests/test_blob_sliced_from_parent_process.js
+++ /dev/null
@@ -1,165 +0,0 @@
-"use strict";
-/* eslint-env mozilla/frame-script */
-
-const { ExtensionTestUtils } = ChromeUtils.import(
-  "resource://testing-common/ExtensionXPCShellUtils.jsm"
-);
-
-ExtensionTestUtils.init(this);
-
-function childFrameScript() {
-  const messageName = "test:blob-slice-test";
-  const blobData = ["So", " ", "many", " ", "blobs!"];
-  const blobText = blobData.join("");
-  const blobType = "text/plain";
-
-  const sliceText = "an";
-
-  function info(msg) {
-    sendAsyncMessage(messageName, { op: "info", msg });
-  }
-
-  function ok(condition, name, diag) {
-    sendAsyncMessage(messageName, { op: "ok", condition, name, diag });
-  }
-
-  function is(a, b, name) {
-    let pass = a == b;
-    let diag = pass ? "" : "got " + a + ", expected " + b;
-    ok(pass, name, diag);
-  }
-
-  function finish(result) {
-    sendAsyncMessage(messageName, { op: "done", result });
-  }
-
-  function grabAndContinue(arg) {
-    testGenerator.next(arg);
-  }
-
-  function* testSteps() {
-    addMessageListener(messageName, grabAndContinue);
-    let message = yield undefined;
-
-    let blob = message.data;
-
-    ok(Blob.isInstance(blob), "Received a Blob");
-    is(blob.size, blobText.length, "Blob has correct length");
-    is(blob.type, blobType, "Blob has correct type");
-
-    info("Reading blob");
-
-    let reader = new FileReader();
-    reader.addEventListener("load", grabAndContinue);
-    reader.readAsText(blob);
-
-    yield undefined;
-
-    is(reader.result, blobText, "Blob has correct data");
-
-    let firstSliceStart = blobData[0].length + blobData[1].length;
-    let firstSliceEnd = firstSliceStart + blobData[2].length;
-
-    let slice = blob.slice(firstSliceStart, firstSliceEnd, blobType);
-
-    ok(Blob.isInstance(slice), "Slice returned a Blob");
-    is(slice.size, blobData[2].length, "Slice has correct length");
-    is(slice.type, blobType, "Slice has correct type");
-
-    info("Reading slice");
-
-    reader = new FileReader();
-    reader.addEventListener("load", grabAndContinue);
-    reader.readAsText(slice);
-
-    yield undefined;
-
-    is(reader.result, blobData[2], "Slice has correct data");
-
-    let secondSliceStart = blobData[2].indexOf("a");
-    let secondSliceEnd = secondSliceStart + sliceText.length;
-
-    slice = slice.slice(secondSliceStart, secondSliceEnd, blobType);
-
-    ok(Blob.isInstance(slice), "Second slice returned a Blob");
-    is(slice.size, sliceText.length, "Second slice has correct length");
-    is(slice.type, blobType, "Second slice has correct type");
-
-    info("Sending second slice");
-    finish(slice);
-  }
-
-  let testGenerator = testSteps();
-  testGenerator.next();
-}
-
-add_task(async function test() {
-  let page = await ExtensionTestUtils.loadContentPage(
-    "data:text/html,<!DOCTYPE HTML><html><body></body></html>",
-    {
-      remote: true,
-    }
-  );
-
-  page.loadFrameScript(childFrameScript);
-
-  const messageName = "test:blob-slice-test";
-  const blobData = ["So", " ", "many", " ", "blobs!"];
-  const blobType = "text/plain";
-
-  const sliceText = "an";
-
-  await new Promise(resolve => {
-    function grabAndContinue(arg) {
-      testGenerator.next(arg);
-    }
-
-    function* testSteps() {
-      let slice = yield undefined;
-
-      ok(Blob.isInstance(slice), "Received a Blob");
-      equal(slice.size, sliceText.length, "Slice has correct size");
-      equal(slice.type, blobType, "Slice has correct type");
-
-      let reader = new FileReader();
-      reader.onload = grabAndContinue;
-      reader.readAsText(slice);
-      yield undefined;
-
-      equal(reader.result, sliceText, "Slice has correct data");
-      resolve();
-    }
-
-    let testGenerator = testSteps();
-    testGenerator.next();
-
-    let mm = page.browser.messageManager;
-    mm.addMessageListener(messageName, function(message) {
-      let data = message.data;
-      switch (data.op) {
-        case "info": {
-          info(data.msg);
-          break;
-        }
-
-        case "ok": {
-          ok(data.condition, data.name + " - " + data.diag);
-          break;
-        }
-
-        case "done": {
-          testGenerator.next(data.result);
-          break;
-        }
-
-        default: {
-          ok(false, "Unknown op: " + data.op);
-          resolve();
-        }
-      }
-    });
-
-    let blob = new Blob(blobData, { type: blobType });
-    mm.sendAsyncMessage(messageName, blob);
-  });
-});
diff --git a/dom/ipc/tests/test_bug1086684.html b/dom/ipc/tests/test_bug1086684.html
new file mode 100644
index 000000000000..750e501511e7
--- /dev/null
+++ b/dom/ipc/tests/test_bug1086684.html
@@ -0,0 +1,108 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test for recursive CPOW-getting-cookie bug</title>
+  <script src="/tests/SimpleTest/SimpleTest.js">
+  </script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+  <script type="application/javascript">
+    "use strict";
+    /* eslint-env mozilla/frame-script */
+
+    SimpleTest.waitForExplicitFinish();
+
+    const childFrameURL =
+      "http://mochi.test:8888/tests/dom/ipc/tests/file_bug1086684.html";
+
+    function childFrameScript() {
+      "use strict";
+
+      let { MockFilePicker } =
+        ChromeUtils.import("resource://specialpowers/MockFilePicker.jsm");
+
+      function parentReady(message) {
+        MockFilePicker.init(content);
+        MockFilePicker.setFiles([message.data.file]);
+        MockFilePicker.returnValue = MockFilePicker.returnOK;
+
+        let input = content.document.getElementById("f");
+        input.addEventListener("change", () => {
+          MockFilePicker.cleanup();
+          let value = input.value;
+          message.target.sendAsyncMessage("testBug1086684:childDone", { value });
+        });
+
+        input.focus();
+        input.click();
+      }
+
+      addMessageListener("testBug1086684:parentReady", function(message) {
+        parentReady(message);
+      });
+    }
+
+    let test;
+    function* testStructure(mm) {
+      let value;
+
+      function testDone(msg) {
+        test.next(msg.data.value);
+      }
+
+      mm.addMessageListener("testBug1086684:childDone",
+                            SpecialPowers.wrapCallback(testDone));
+
+      let blob = new Blob([]);
+      let file = new File([blob], "helloworld.txt", { type: "text/plain" });
+
+      mm.sendAsyncMessage("testBug1086684:parentReady", { file });
+      value = yield;
+
+      // Note that the "helloworld.txt" passed in above doesn't affect the
+      // 'value' getter. Because we're mocking a file using a blob, we ask the
+      // blob for its path, which is the empty string.
+      is(value, "", "got the right answer and didn't crash");
+
+      SimpleTest.finish();
+    }
+
+    function runTests() {
+      info("Browser prefs set.");
+
+      let iframe = document.createElement("iframe");
+      SpecialPowers.wrap(iframe).mozbrowser = true;
+      iframe.id = "iframe";
+      iframe.src = childFrameURL;
+
+      iframe.addEventListener("mozbrowserloadend", function() {
+        info("Got iframe load event.");
+        let mm = SpecialPowers.getBrowserFrameMessageManager(iframe);
+        mm.loadFrameScript("data:,(" + encodeURI(childFrameScript.toString()) + ")();",
+                           false);
+
+        test = testStructure(mm);
+        test.next();
+      });
+
+      document.body.appendChild(iframe);
+    }
+
+    addEventListener("load", function() {
+      info("Got load event.");
+
+      SpecialPowers.addPermission("browser", true, document);
+      SpecialPowers.pushPrefEnv({
+        "set": [
+          ["dom.ipc.browser_frames.oop_by_default", true],
+          ["dom.mozBrowserFramesEnabled", true],
+          ["network.disable.ipc.security", true],
+          ["browser.pagethumbnails.capturing_disabled", true],
+        ],
+      }, runTests);
+    });
+  </script>
+</body>
+</html>
diff --git a/dom/ipc/tests/test_bug1086684.js b/dom/ipc/tests/test_bug1086684.js
deleted file mode 100644
index 6f8c643463c1..000000000000
--- a/dom/ipc/tests/test_bug1086684.js
+++ /dev/null
@@ -1,101 +0,0 @@
-"use strict";
-/* eslint-env mozilla/frame-script */
-
-const { AddonTestUtils } = ChromeUtils.import(
-  "resource://testing-common/AddonTestUtils.jsm"
-);
-const { ExtensionTestUtils } = ChromeUtils.import(
-  "resource://testing-common/ExtensionXPCShellUtils.jsm"
-);
-
-AddonTestUtils.init(this);
-ExtensionTestUtils.init(this);
-
-ChromeUtils.import(
-  "resource://gre/modules/ContentPrefServiceParent.jsm"
-).ContentPrefServiceParent.init();
-
-const childFramePath = "/file_bug1086684.html";
-const childFrameURL = "http://example.com" + childFramePath;
-
-const childFrameContents = `<!DOCTYPE html>
-<html>
-<head>
-  <meta charset="UTF-8">
-</head>
-<body>
-<div id="content">
-    <input type="file" id="f">
-</div>
-</body>
-</html>`;
-
-const server = AddonTestUtils.createHttpServer({ hosts: ["example.com"] });
-server.registerPathHandler(childFramePath, (request, response) => {
-  response.write(childFrameContents);
-});
-
-function childFrameScript() {
-  "use strict";
-
-  let { MockFilePicker } = ChromeUtils.import(
-    "resource://testing-common/MockFilePicker.jsm"
-  );
-
-  function parentReady(message) {
-    MockFilePicker.init(content);
-    MockFilePicker.setFiles([message.data.file]);
-    MockFilePicker.returnValue = MockFilePicker.returnOK;
-
-    let input = content.document.getElementById("f");
-    input.addEventListener("change", () => {
-      MockFilePicker.cleanup();
-      let value = input.value;
-      message.target.sendAsyncMessage("testBug1086684:childDone", { value });
-    });
-
-    input.focus();
-    input.click();
-  }
-
-  addMessageListener("testBug1086684:parentReady", function(message) {
-    parentReady(message);
-  });
-}
-
-add_task(async function() {
-  let page = await ExtensionTestUtils.loadContentPage(childFrameURL, {
-    remote: true,
-  });
-
-  page.loadFrameScript(childFrameScript);
-
-  await new Promise(resolve => {
-    let test;
-    function* testStructure(mm) {
-      let value;
-
-      function testDone(msg) {
-        test.next(msg.data.value);
-      }
-
-      mm.addMessageListener("testBug1086684:childDone", testDone);
-
-      let blob = new Blob([]);
-      let file = new File([blob], "helloworld.txt", { type: "text/plain" });
-
-      mm.sendAsyncMessage("testBug1086684:parentReady", { file });
-      value = yield;
-
-      // Note that the "helloworld.txt" passed in above doesn't affect the
-      // 'value' getter. Because we're mocking a file using a blob, we ask the
-      // blob for its path, which is the empty string.
-      equal(value, "", "got the right answer and didn't crash");
-
-      resolve();
-    }
-
-    test = testStructure(page.browser.messageManager);
-    test.next();
-  });
-});
diff --git a/dom/ipc/tests/test_child_docshell.html b/dom/ipc/tests/test_child_docshell.html
new file mode 100644
index 000000000000..bc4dbb2e4d24
--- /dev/null
+++ b/dom/ipc/tests/test_child_docshell.html
@@ -0,0 +1,90 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+-->
+<head>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+<script type="application/javascript">
+"use strict";
+/* eslint-env mozilla/frame-script */
+
+SimpleTest.waitForExplicitFinish();
+SpecialPowers.addPermission("browser", true, document);
+SpecialPowers.pushPrefEnv({"set": [
+  ["dom.mozBrowserFramesEnabled", true],
+  ["network.disable.ipc.security", true],
+  ["dom.ipc.tabs.disabled", false],
+]}, function() {
+  var iframe =  document.createElementNS("http://www.w3.org/1999/xhtml", "iframe");
+  iframe.setAttribute("remote", "true");
+  SpecialPowers.wrap(iframe).mozbrowser = true;
+  document.documentElement.appendChild(iframe);
+
+  var mm = SpecialPowers.getBrowserFrameMessageManager(iframe);
+  mm.addMessageListener("chromeEventHandler", function(msg) {
+    msg = SpecialPowers.wrap(msg);
+    var result = msg.json;
+    is(result.processType, SpecialPowers.Ci.nsIXULRuntime.PROCESS_TYPE_CONTENT,
+       "The frame script is running in a real distinct child process");
+    ok(result.hasCorrectInterface,
+       "docshell.chromeEventHandler has EventTarget interface");
+  });
+
+
+  mm.addMessageListener("DOMWindowCreatedReceived", function(msg) {
+    msg = SpecialPowers.wrap(msg);
+    ok(true, "the chrome event handler looks functional");
+    var result = msg.json;
+    ok(result.stableChromeEventHandler, "docShell.chromeEventHandler is stable");
+    ok(result.iframeHasNewDocShell, "iframe spawns a new docShell");
+    ok(result.iframeHasSameChromeEventHandler, "but iframe has the same chrome event handler");
+    SimpleTest.finish();
+  });
+  // Inject a frame script in the child process:
+  mm.loadFrameScript("data:,new " + function ContentScriptScope() {
+    var chromeEventHandler = docShell.chromeEventHandler;
+    sendAsyncMessage("chromeEventHandler", {
+      processType: Services.appinfo.processType,
+      hasCorrectInterface: chromeEventHandler &&
+                           EventTarget.isInstance(chromeEventHandler),
+    });
+
+    /*
+      Ensure that this chromeEventHandler actually works,
+      by creating a new window and listening for its DOMWindowCreated event
+    */
+    chromeEventHandler.addEventListener("DOMWindowCreated", function listener(evt) {
+      if (evt.target == content.document) {
+        return;
+      }
+      chromeEventHandler.removeEventListener("DOMWindowCreated", listener);
+      let new_win = evt.target.defaultView;
+      let new_docShell = new_win.docShell;
+      sendAsyncMessage("DOMWindowCreatedReceived", {
+        stableChromeEventHandler: chromeEventHandler === docShell.chromeEventHandler,
+        iframeHasNewDocShell: new_docShell !== docShell,
+        iframeHasSameChromeEventHandler: new_docShell.chromeEventHandler === chromeEventHandler,
+      });
+    });
+
+    function go() {
+      let i = content.document.createElement("iframe");
+      i.setAttribute("src", "data:text/html,foo");
+      content.document.documentElement.appendChild(i);
+    }
+
+    if (content.document.readyState == "complete") {
+      go();
+    } else {
+      addEventListener("load", go, { once: true, capture: true });
+    }
+  }, false);
+});
+
+</script>
+</body>
+</html>
diff --git a/dom/ipc/tests/test_child_docshell.js b/dom/ipc/tests/test_child_docshell.js
deleted file mode 100644
index 64a69fede972..000000000000
--- a/dom/ipc/tests/test_child_docshell.js
+++ /dev/null
@@ -1,89 +0,0 @@
-"use strict";
-/* eslint-env mozilla/frame-script */
-
-const { ExtensionTestUtils } = ChromeUtils.import(
-  "resource://testing-common/ExtensionXPCShellUtils.jsm"
-);
-
-ExtensionTestUtils.init(this);
-
-add_task(async function test() {
-  let page = await ExtensionTestUtils.loadContentPage("about:blank", {
-    remote: true,
-  });
-
-  await new Promise(resolve => {
-    let mm = page.browser.messageManager;
-    mm.addMessageListener("chromeEventHandler", function(msg) {
-      var result = msg.json;
-      equal(
-        result.processType,
-        Ci.nsIXULRuntime.PROCESS_TYPE_CONTENT,
-        "The frame script is running in a real distinct child process"
-      );
-      ok(
-        result.hasCorrectInterface,
-        "docshell.chromeEventHandler has EventTarget interface"
-      );
-    });
-
-    mm.addMessageListener("DOMWindowCreatedReceived", function(msg) {
-      ok(true, "the chrome event handler looks functional");
-      var result = msg.json;
-      ok(
-        result.stableChromeEventHandler,
-        "docShell.chromeEventHandler is stable"
-      );
-      ok(result.iframeHasNewDocShell, "iframe spawns a new docShell");
-      ok(
-        result.iframeHasSameChromeEventHandler,
-        "but iframe has the same chrome event handler"
-      );
-      resolve();
-    });
-
-    // Inject a frame script in the child process:
-    page.loadFrameScript(async function() {
-      var chromeEventHandler = docShell.chromeEventHandler;
-      sendAsyncMessage("chromeEventHandler", {
-        processType: Services.appinfo.processType,
-        hasCorrectInterface:
-          chromeEventHandler && EventTarget.isInstance(chromeEventHandler),
-      });
-
-      /*
-        Ensure that this chromeEventHandler actually works,
-        by creating a new window and listening for its DOMWindowCreated event
-      */
-      chromeEventHandler.addEventListener("DOMWindowCreated", function listener(
-        evt
-      ) {
-        if (evt.target == content.document) {
-          return;
-        }
-        chromeEventHandler.removeEventListener("DOMWindowCreated", listener);
-        let new_win = evt.target.defaultView;
-        let new_docShell = new_win.docShell;
-        sendAsyncMessage("DOMWindowCreatedReceived", {
-          stableChromeEventHandler:
-            chromeEventHandler === docShell.chromeEventHandler,
-          iframeHasNewDocShell: new_docShell !== docShell,
-          iframeHasSameChromeEventHandler:
-            new_docShell.chromeEventHandler === chromeEventHandler,
-        });
-      });
-
-      if (content.document.readyState != "complete") {
-        await new Promise(res =>
-          addEventListener("load", res, { once: true, capture: true })
-        );
-      }
-
-      let iframe = content.document.createElement("iframe");
-      iframe.setAttribute("src", "data:text/html,foo");
-      content.document.documentElement.appendChild(iframe);
-    });
-  });
-
-  await page.close();
-});
diff --git a/dom/ipc/tests/test_cpow_cookies.html b/dom/ipc/tests/test_cpow_cookies.html
new file mode 100644
index 000000000000..1d92211bd352
--- /dev/null
+++ b/dom/ipc/tests/test_cpow_cookies.html
@@ -0,0 +1,90 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test for recursive CPOW-getting-cookie bug</title>
+  <script src="/tests/SimpleTest/SimpleTest.js">
+  </script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+  <script type="application/javascript">
+    "use strict";
+    /* eslint-env mozilla/frame-script */
+
+    SimpleTest.waitForExplicitFinish();
+
+    const childFrameURL =
+      "data:text/html,<!DOCTYPE HTML><html><body></body></html>";
+
+    function childFrameScript() {
+      "use strict";
+
+      function test1(message) {
+        // NB: This is a no-op because we're a data: document with a null
+        // principal.
+        content.document.cookie = "a=b";
+        message.target.sendAsyncMessage("testCPOWCookies:test1Finished", { pass: true });
+      }
+
+      addMessageListener("testCPOWCookies:test1", function(message) {
+        test1(message);
+      });
+    }
+
+    let test;
+    function* testStructure(mm) {
+      let lastResult;
+
+      function testDone(msg) {
+        test.next(msg.data);
+      }
+
+      mm.addMessageListener("testCPOWCookies:test1Finished",
+                            SpecialPowers.wrapCallback(testDone));
+
+      mm.sendAsyncMessage("testCPOWCookies:test1", {});
+      lastResult = yield;
+      ok(lastResult.pass, "got the right answer and didn't crash");
+
+      SimpleTest.finish();
+    }
+
+    function runTests() {
+      info("Browser prefs set.");
+
+      let iframe = document.createElement("iframe");
+      SpecialPowers.wrap(iframe).mozbrowser = true;
+      iframe.id = "iframe";
+      iframe.src = childFrameURL;
+
+      iframe.addEventListener("mozbrowserloadend", function() {
+        info("Got iframe load event.");
+        let mm = SpecialPowers.getBrowserFrameMessageManager(iframe);
+        mm.loadFrameScript("data:,(" + encodeURI(childFrameScript.toString()) + ")();",
+                           false);
+
+        test = testStructure(mm);
+        test.next();
+      });
+
+      document.body.appendChild(iframe);
+    }
+
+    addEventListener("load", function() {
+      info("Got load event.");
+
+      SpecialPowers.addPermission("browser", true, document);
+      SpecialPowers.pushPrefEnv({
+        "set": [
+          ["dom.ipc.browser_frames.oop_by_default", true],
+          ["dom.mozBrowserFramesEnabled", true],
+          ["network.disable.ipc.security", true],
+          ["browser.pagethumbnails.capturing_disabled", true],
+          ["security.data_uri.block_toplevel_data_uri_navigations", false],
+        ],
+      }, runTests);
+    });
+  </script>
+</body>
+</html>
diff --git a/dom/ipc/tests/xpcshell.ini b/dom/ipc/tests/xpcshell.ini
index f0a20158c15d..297052b0d1b9 100644
--- a/dom/ipc/tests/xpcshell.ini
+++ b/dom/ipc/tests/xpcshell.ini
@@ -1,7 +1,2 @@
 [test_sharedMap.js]
 skip-if = os == "android" && processor == "x86_64"
-
-[test_blob_sliced_from_child_process.js]
-[test_blob_sliced_from_parent_process.js]
-[test_bug1086684.js]
-[test_child_docshell.js]
diff --git a/dom/messagechannel/tests/mm_messageChannelParent.js b/dom/messagechannel/tests/mm_messageChannelParent.js
index 5de4211f0247..e63bece9fce9 100644
--- a/dom/messagechannel/tests/mm_messageChannelParent.js
+++ b/dom/messagechannel/tests/mm_messageChannelParent.js
@@ -61,7 +61,9 @@ function basic_test(finish) {
   let channel = new MessageChannel();
   port = channel.port2;
   mm.addMessageListener("BasicTest:FinishPrepare", finishPrepare);
-  mm.sendAsyncMessage("BasicTest:PortCreated", {}, {}, [channel.port1]);
+  mm.sendAsyncMessage("BasicTest:PortCreated", {}, {}, undefined, [
+    channel.port1,
+  ]);
 }
 
 // Communicate with closed port.
@@ -85,7 +87,9 @@ function close_test(finish) {
   let channel = new MessageChannel();
   port = channel.port2;
   mm.addMessageListener("CloseTest:FinishPrepare", finishPrepare);
-  mm.sendAsyncMessage("CloseTest:PortCreated", {}, {}, [channel.port1]);
+  mm.sendAsyncMessage("CloseTest:PortCreated", {}, {}, undefined, [
+    channel.port1,
+  ]);
 }
 
 // Empty transferable object
@@ -99,7 +103,7 @@ function empty_transferable(finish) {
   };
 
   mm.addMessageListener("EmptyTest:FinishPrepare", finishPrepare);
-  mm.sendAsyncMessage("EmptyTest:PortCreated", {}, {}, []);
+  mm.sendAsyncMessage("EmptyTest:PortCreated", {}, {}, undefined, []);
 }
 
 // Not transferable object.
@@ -112,7 +116,9 @@ function not_transferable(finish) {
   };
 
   mm.addMessageListener("NotTransferableTest:FinishPrepare", finishPrepare);
-  mm.sendAsyncMessage("NotTransferableTest:PortCreated", {}, {}, [""]);
+  mm.sendAsyncMessage("NotTransferableTest:PortCreated", {}, {}, undefined, [
+    "",
+  ]);
 }
 
 /*
diff --git a/dom/network/tests/chrome.ini b/dom/network/tests/chrome.ini
index 1be7af7b2556..70e787f79181 100644
--- a/dom/network/tests/chrome.ini
+++ b/dom/network/tests/chrome.ini
@@ -2,7 +2,6 @@
 support-files =
   tcpsocket_test.jsm
   test_tcpsocket_client_and_server_basics.js
-  file_postMessage_opener.html
   file_udpsocket_iframe.html
 
 [test_tcpsocket_jsm.html]
diff --git a/dom/network/tests/file_postMessage_opener.html b/dom/network/tests/file_postMessage_opener.html
deleted file mode 100644
index 87359e25c2e3..000000000000
--- a/dom/network/tests/file_postMessage_opener.html
+++ /dev/null
@@ -1,11 +0,0 @@
-<!DOCTYPE html>
-<html lang="en">
-<head>
-  <meta charset="UTF-8">
-  <script>
-    opener.postMessage("hello", "*");
-  </script>
-</head>
-<body>
-</body>
-</html>
diff --git a/dom/network/tests/test_udpsocket.html b/dom/network/tests/test_udpsocket.html
index afd6b9cb4483..bc1027c3f0b9 100644
--- a/dom/network/tests/test_udpsocket.html
+++ b/dom/network/tests/test_udpsocket.html
@@ -321,44 +321,38 @@ function testOpenWithoutClose() {
   return Promise.all(closed);
 }
 
-function awaitEvent(target, event) {
-  return new Promise(resolve => {
-    target.addEventListener(event, resolve, { once: true });
-  });
-}
-
-async function testBFCache() {
+function testBFCache() {
   info('test for bfcache behavior');
 
   let socket = new UDPSocket();
 
-  await socket.opened;
+  return socket.opened.then(function() {
+    let iframe = document.getElementById('iframe');
+    SpecialPowers.wrap(iframe).mozbrowser = true;
+    iframe.src = 'file_udpsocket_iframe.html?' + socket.localPort;
 
-  let win = window.open(`file_udpsocket_iframe.html?${socket.localPort}`);
+    return new Promise(function(resolve, reject) {
+      socket.addEventListener('message', function(msg) {
+        iframe.src = 'about:blank';
+        iframe.addEventListener('load', function() {
+          socket.send(HELLO_WORLD, '127.0.0.1', msg.remotePort);
 
-  let msg = await awaitEvent(socket, "message");
+          function recv_again_callback(message) {
+            socket.removeEventListener('message', recv_again_callback);
+            ok(false, 'should not receive packet after page unload');
+          }
 
-  win.location = "file_postMessage_opener.html";
-  await awaitEvent(window, "message");
+          socket.addEventListener('message', recv_again_callback);
 
-  socket.send(HELLO_WORLD, '127.0.0.1', msg.remotePort);
-
-  await new Promise(resolve => {
-    function recv_again_callback(message) {
-      socket.removeEventListener('message', recv_again_callback);
-      ok(false, 'should not receive packet after page unload');
-    }
-
-    socket.addEventListener('message', recv_again_callback);
-
-    let timeout = setTimeout(function() {
-      socket.removeEventListener('message', recv_again_callback);
-      socket.close();
-      resolve();
-    }, 5000);
+          let timeout = setTimeout(function() {
+            socket.removeEventListener('message', recv_again_callback);
+            socket.close();
+            resolve();
+          }, 5000);
+        }, {once: true});
+      }, {once: true});
+    });
   });
-
-  win.close();
 }
 
 function runTest() {
diff --git a/dom/presentation/Presentation.cpp b/dom/presentation/Presentation.cpp
index 5c0efd7693de..fe915eb9fb9d 100644
--- a/dom/presentation/Presentation.cpp
+++ b/dom/presentation/Presentation.cpp
@@ -124,6 +124,7 @@ bool Presentation::HasReceiverSupport() const {
   }
 
   if (!StaticPrefs::dom_presentation_testing_simulate_receiver() &&
+      !docShell->GetIsInMozBrowser() &&
       !docShell->GetIsTopLevelContentDocShell()) {
     return false;
   }
diff --git a/dom/presentation/tests/mochitest/test_presentation_1ua_connection_wentaway.js b/dom/presentation/tests/mochitest/test_presentation_1ua_connection_wentaway.js
index 8234b30a9697..9464a8d9a7e2 100644
--- a/dom/presentation/tests/mochitest/test_presentation_1ua_connection_wentaway.js
+++ b/dom/presentation/tests/mochitest/test_presentation_1ua_connection_wentaway.js
@@ -231,6 +231,7 @@ SpecialPowers.pushPermissions(
           ["dom.presentation.controller.enabled", true],
           ["dom.presentation.receiver.enabled", true],
           ["dom.presentation.test.enabled", true],
+          ["dom.mozBrowserFramesEnabled", true],
           ["dom.ipc.tabs.disabled", false],
           ["network.disable.ipc.security", true],
           ["dom.presentation.test.stage", 0],
diff --git a/dom/presentation/tests/mochitest/test_presentation_1ua_sender_and_receiver.js b/dom/presentation/tests/mochitest/test_presentation_1ua_sender_and_receiver.js
index c9fa2d1b3a1b..24900bd4b326 100644
--- a/dom/presentation/tests/mochitest/test_presentation_1ua_sender_and_receiver.js
+++ b/dom/presentation/tests/mochitest/test_presentation_1ua_sender_and_receiver.js
@@ -513,6 +513,7 @@ SpecialPowers.pushPermissions(
           ["dom.presentation.receiver.enabled", true],
           ["dom.presentation.test.enabled", true],
           ["dom.presentation.test.stage", 0],
+          ["dom.mozBrowserFramesEnabled", true],
           ["network.disable.ipc.security", true],
           ["media.navigator.permission.disabled", true],
         ],
diff --git a/dom/presentation/tests/mochitest/test_presentation_dc_receiver.html b/dom/presentation/tests/mochitest/test_presentation_dc_receiver.html
index 3892e2824c94..2053ffccd11e 100644
--- a/dom/presentation/tests/mochitest/test_presentation_dc_receiver.html
+++ b/dom/presentation/tests/mochitest/test_presentation_dc_receiver.html
@@ -130,6 +130,7 @@ SpecialPowers.pushPermissions([
                                       ["dom.presentation.controller.enabled", false],
                                       ["dom.presentation.receiver.enabled", true],
                                       ["dom.presentation.session_transport.data_channel.enable", true],
+                                      ["dom.mozBrowserFramesEnabled", true],
                                       ["network.disable.ipc.security", true]]},
                             runTests);
 });
diff --git a/dom/presentation/tests/mochitest/test_presentation_dc_receiver_oop.html b/dom/presentation/tests/mochitest/test_presentation_dc_receiver_oop.html
index 309598ec996f..c77c5de7dcb5 100644
--- a/dom/presentation/tests/mochitest/test_presentation_dc_receiver_oop.html
+++ b/dom/presentation/tests/mochitest/test_presentation_dc_receiver_oop.html
@@ -199,6 +199,7 @@ SpecialPowers.pushPermissions([
                                       ["dom.presentation.controller.enabled", false],
                                       ["dom.presentation.receiver.enabled", true],
                                       ["dom.presentation.session_transport.data_channel.enable", true],
+                                      ["dom.mozBrowserFramesEnabled", true],
                                       ["network.disable.ipc.security", true],
                                       ["dom.ipc.browser_frames.oop_by_default", true],
                                       ["presentation.receiver.loading.timeout", 5000000]]},
diff --git a/dom/presentation/tests/mochitest/test_presentation_fingerprinting_resistance.html b/dom/presentation/tests/mochitest/test_presentation_fingerprinting_resistance.html
index 47644f3465ba..303b7f062791 100644
--- a/dom/presentation/tests/mochitest/test_presentation_fingerprinting_resistance.html
+++ b/dom/presentation/tests/mochitest/test_presentation_fingerprinting_resistance.html
@@ -26,6 +26,7 @@ let setup = async () => {
       ["dom.presentation.receiver.enabled", true],
       ["dom.presentation.test.enabled", true],
       ["dom.presentation.test.stage", 0],
+      ["dom.mozBrowserFramesEnabled", true],
       ["network.disable.ipc.security", true],
     ],
   });
diff --git a/dom/presentation/tests/mochitest/test_presentation_receiver_auxiliary_navigation.js b/dom/presentation/tests/mochitest/test_presentation_receiver_auxiliary_navigation.js
index 41dcc05f0890..072b0c0ccc99 100644
--- a/dom/presentation/tests/mochitest/test_presentation_receiver_auxiliary_navigation.js
+++ b/dom/presentation/tests/mochitest/test_presentation_receiver_auxiliary_navigation.js
@@ -82,6 +82,7 @@ SpecialPowers.pushPermissions(
           ["dom.presentation.enabled", true],
           ["dom.presentation.controller.enabled", true],
           ["dom.presentation.receiver.enabled", true],
+          ["dom.mozBrowserFramesEnabled", true],
           ["network.disable.ipc.security", true],
           ["dom.presentation.session_transport.data_channel.enable", false],
         ],
diff --git a/dom/presentation/tests/mochitest/test_presentation_tcp_receiver.html b/dom/presentation/tests/mochitest/test_presentation_tcp_receiver.html
index 8f2f14fa0628..47ba1231da34 100644
--- a/dom/presentation/tests/mochitest/test_presentation_tcp_receiver.html
+++ b/dom/presentation/tests/mochitest/test_presentation_tcp_receiver.html
@@ -121,6 +121,7 @@ SpecialPowers.pushPermissions([
   SpecialPowers.pushPrefEnv({ "set": [["dom.presentation.enabled", true],
                                       ["dom.presentation.controller.enabled", false],
                                       ["dom.presentation.receiver.enabled", true],
+                                      ["dom.mozBrowserFramesEnabled", true],
                                       ["network.disable.ipc.security", true],
                                       ["dom.presentation.session_transport.data_channel.enable", false]]},
                             runTests);
diff --git a/dom/presentation/tests/mochitest/test_presentation_tcp_receiver_establish_connection_error.html b/dom/presentation/tests/mochitest/test_presentation_tcp_receiver_establish_connection_error.html
index dc4b99615d90..1bbf7577f651 100644
--- a/dom/presentation/tests/mochitest/test_presentation_tcp_receiver_establish_connection_error.html
+++ b/dom/presentation/tests/mochitest/test_presentation_tcp_receiver_establish_connection_error.html
@@ -95,6 +95,7 @@ SpecialPowers.pushPermissions([
   SpecialPowers.pushPrefEnv({ "set": [["dom.presentation.enabled", true],
                                       ["dom.presentation.receiver.enabled", true],
                                       ["dom.presentation.session_transport.data_channel.enable", false],
+                                      ["dom.mozBrowserFramesEnabled", true],
                                       ["network.disable.ipc.security", true]]},
                             runTests);
 });
diff --git a/dom/presentation/tests/mochitest/test_presentation_tcp_receiver_establish_connection_unknown_content_type.js b/dom/presentation/tests/mochitest/test_presentation_tcp_receiver_establish_connection_unknown_content_type.js
index 9394c8642449..00ec85d48ab3 100644
--- a/dom/presentation/tests/mochitest/test_presentation_tcp_receiver_establish_connection_unknown_content_type.js
+++ b/dom/presentation/tests/mochitest/test_presentation_tcp_receiver_establish_connection_unknown_content_type.js
@@ -107,6 +107,7 @@ SpecialPowers.pushPermissions(
           ["dom.presentation.controller.enabled", true],
           ["dom.presentation.receiver.enabled", true],
           ["dom.presentation.session_transport.data_channel.enable", false],
+          ["dom.mozBrowserFramesEnabled", true],
           ["network.disable.ipc.security", true],
           ["dom.ipc.tabs.disabled", false],
         ],
diff --git a/dom/presentation/tests/mochitest/test_presentation_tcp_receiver_oop.html b/dom/presentation/tests/mochitest/test_presentation_tcp_receiver_oop.html
index bb0d332544a9..363acc94f7ef 100644
--- a/dom/presentation/tests/mochitest/test_presentation_tcp_receiver_oop.html
+++ b/dom/presentation/tests/mochitest/test_presentation_tcp_receiver_oop.html
@@ -162,6 +162,7 @@ SpecialPowers.pushPermissions([
                                       ["dom.presentation.controller.enabled", false],
                                       ["dom.presentation.receiver.enabled", true],
                                       ["dom.presentation.session_transport.data_channel.enable", false],
+                                      ["dom.mozBrowserFramesEnabled", true],
                                       ["network.disable.ipc.security", true],
                                       ["dom.ipc.browser_frames.oop_by_default", true]]},
                             runTests);
diff --git a/dom/presentation/tests/mochitest/test_presentation_terminate.js b/dom/presentation/tests/mochitest/test_presentation_terminate.js
index 1d34d2b00e33..25582e6e9f72 100644
--- a/dom/presentation/tests/mochitest/test_presentation_terminate.js
+++ b/dom/presentation/tests/mochitest/test_presentation_terminate.js
@@ -315,6 +315,7 @@ SpecialPowers.pushPermissions(
           ["dom.presentation.controller.enabled", true],
           ["dom.presentation.receiver.enabled", true],
           ["dom.presentation.test.enabled", true],
+          ["dom.mozBrowserFramesEnabled", true],
           ["network.disable.ipc.security", true],
           ["dom.ipc.tabs.disabled", false],
           ["dom.presentation.test.stage", 0],
diff --git a/dom/presentation/tests/mochitest/test_presentation_terminate_establish_connection_error.js b/dom/presentation/tests/mochitest/test_presentation_terminate_establish_connection_error.js
index b12b6d748a5e..df8ae21350c8 100644
--- a/dom/presentation/tests/mochitest/test_presentation_terminate_establish_connection_error.js
+++ b/dom/presentation/tests/mochitest/test_presentation_terminate_establish_connection_error.js
@@ -256,6 +256,7 @@ SpecialPowers.pushPermissions(
           ["dom.presentation.controller.enabled", true],
           ["dom.presentation.receiver.enabled", true],
           ["dom.presentation.test.enabled", true],
+          ["dom.mozBrowserFramesEnabled", true],
           ["network.disable.ipc.security", true],
           ["dom.ipc.tabs.disabled", false],
           ["dom.presentation.test.stage", 0],
diff --git a/dom/push/PushComponents.jsm b/dom/push/PushComponents.jsm
index 890fde8fb777..1c99e7711f4f 100644
--- a/dom/push/PushComponents.jsm
+++ b/dom/push/PushComponents.jsm
@@ -225,7 +225,7 @@ Object.assign(PushServiceParent.prototype, {
     if (!this._isValidMessage(message)) {
       return;
     }
-    let { name, target, data } = message;
+    let { name, principal, target, data } = message;
     if (name === "Push:NotificationForOriginShown") {
       this.notificationForOriginShown(data);
       return;
@@ -238,7 +238,7 @@ Object.assign(PushServiceParent.prototype, {
       this.reportDeliveryError(data.messageId, data.reason);
       return;
     }
-    this._handleRequest(name, data.principal, data)
+    this._handleRequest(name, principal, data)
       .then(
         result => {
           target.sendAsyncMessage(this._getResponseName(name, "OK"), {
@@ -382,30 +382,42 @@ Object.assign(PushServiceContent.prototype, {
 
   subscribeWithKey(scope, principal, key, callback) {
     let requestID = this._addRequest(callback);
-    this._mm.sendAsyncMessage("Push:Register", {
-      scope,
-      appServerKey: key,
-      requestID,
-      principal,
-    });
+    this._mm.sendAsyncMessage(
+      "Push:Register",
+      {
+        scope,
+        appServerKey: key,
+        requestID,
+      },
+      null,
+      principal
+    );
   },
 
   unsubscribe(scope, principal, callback) {
     let requestID = this._addRequest(callback);
-    this._mm.sendAsyncMessage("Push:Unregister", {
-      scope,
-      requestID,
-      principal,
-    });
+    this._mm.sendAsyncMessage(
+      "Push:Unregister",
+      {
+        scope,
+        requestID,
+      },
+      null,
+      principal
+    );
   },
 
   getSubscription(scope, principal, callback) {
     let requestID = this._addRequest(callback);
-    this._mm.sendAsyncMessage("Push:Registration", {
-      scope,
-      requestID,
-      principal,
-    });
+    this._mm.sendAsyncMessage(
+      "Push:Registration",
+      {
+        scope,
+        requestID,
+      },
+      null,
+      principal
+    );
   },
 
   clearForDomain(domain, callback) {
diff --git a/dom/push/test/mockpushserviceparent.js b/dom/push/test/mockpushserviceparent.js
index 1c833ab2a72a..cda7b707f6aa 100644
--- a/dom/push/test/mockpushserviceparent.js
+++ b/dom/push/test/mockpushserviceparent.js
@@ -120,12 +120,7 @@ var MockService = {
       sendAsyncMessage("service-request", {
         name,
         id,
-        // The request params from the real push service may contain a
-        // principal, which cannot be passed to the unprivileged
-        // mochitest scope, and will cause the message to be dropped if
-        // present. The mochitest scope fortunately does not need the
-        // principal, though, so set it to null before sending.
-        params: Object.assign({}, params, { principal: null }),
+        params,
       });
     });
   },
diff --git a/dom/tests/browser/browser_frame_elements.js b/dom/tests/browser/browser_frame_elements.js
index 331ac6d0b7fb..3bbd9ddebd01 100644
--- a/dom/tests/browser/browser_frame_elements.js
+++ b/dom/tests/browser/browser_frame_elements.js
@@ -22,6 +22,7 @@ add_task(async function test() {
     }
 
     await SpecialPowers.spawn(browser, [], startTests);
+    await mozBrowserTests(browser);
   });
 });
 
@@ -77,3 +78,32 @@ function startTests() {
     "gWindow is parent"
   );
 }
+
+async function mozBrowserTests(browser) {
+  info("Granting special powers for mozbrowser");
+  await SpecialPowers.addPermission("browser", true, TEST_URI);
+  Services.prefs.setBoolPref("dom.mozBrowserFramesEnabled", true);
+  Services.prefs.setBoolPref("network.disable.ipc.security", true);
+
+  await SpecialPowers.spawn(browser, [], function() {
+    info("Checking mozbrowser iframe");
+    let mozBrowserFrame = content.document.createElement("iframe");
+    mozBrowserFrame.setAttribute("mozbrowser", "");
+    content.document.body.appendChild(mozBrowserFrame);
+    Assert.equal(
+      mozBrowserFrame.contentWindow.top,
+      mozBrowserFrame.contentWindow,
+      "Mozbrowser top == iframe window"
+    );
+    Assert.equal(
+      mozBrowserFrame.contentWindow.parent,
+      mozBrowserFrame.contentWindow,
+      "Mozbrowser parent == iframe window"
+    );
+  });
+
+  info("Revoking special powers for mozbrowser");
+  Services.prefs.clearUserPref("dom.mozBrowserFramesEnabled");
+  Services.prefs.clearUserPref("network.disable.ipc.security");
+  await SpecialPowers.removePermission("browser", TEST_URI);
+}
diff --git a/layout/base/tests/bug921928_event_target_iframe_apps_oop.html b/layout/base/tests/bug921928_event_target_iframe_apps_oop.html
new file mode 100644
index 000000000000..2a6a7d5a6d56
--- /dev/null
+++ b/layout/base/tests/bug921928_event_target_iframe_apps_oop.html
@@ -0,0 +1,8 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test companion for bug 921928</title>
+</head>
+<body>
+</body>
+</html>
diff --git a/layout/base/tests/mochitest.ini b/layout/base/tests/mochitest.ini
index 0e7336b8deea..5810876b3069 100644
--- a/layout/base/tests/mochitest.ini
+++ b/layout/base/tests/mochitest.ini
@@ -143,6 +143,9 @@ support-files = bug1448730.html
 support-files = file_dynamic_toolbar_max_height.html
 [test_emulateMedium.html]
 [test_emulate_color_scheme.html]
+[test_event_target_iframe_oop.html]
+skip-if = e10s # bug 1020135, nested oop iframes not supported
+support-files = bug921928_event_target_iframe_apps_oop.html
 [test_event_target_radius.html]
 [test_flush_on_paint.html]
 skip-if = true # Bug 688128
@@ -409,6 +412,7 @@ support-files =
   bug1529492-1.html
   bug1529492-1-ref.html
 
+[test_remote_frame.html]
 [test_resize_flush.html]
 support-files = resize_flush_iframe.html
 [test_scroll_event_ordering.html]
diff --git a/layout/base/tests/test_event_target_iframe_oop.html b/layout/base/tests/test_event_target_iframe_oop.html
index 562433c9554c..c6c3b41b8c5b 100644
--- a/layout/base/tests/test_event_target_iframe_oop.html
+++ b/layout/base/tests/test_event_target_iframe_oop.html
@@ -49,6 +49,7 @@ var prefs = [
   ["ui.mouse.radius.rightmm", 4],
   ["ui.mouse.radius.bottommm", 4],
   ["ui.mouse.radius.visitedweight", 50],
+  ["dom.mozBrowserFramesEnabled", true]
 ];
 
 var eventTarget;
diff --git a/layout/base/tests/test_remote_frame.html b/layout/base/tests/test_remote_frame.html
new file mode 100644
index 000000000000..7eeb6ce65489
--- /dev/null
+++ b/layout/base/tests/test_remote_frame.html
@@ -0,0 +1,66 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/WindowSnapshot.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+  <style>
+  div, iframe {
+    position:absolute;
+    left:0; top:50px;
+    width:400px; height:400px;
+    transform: translateY(50px);
+    border:5px solid black;
+  }
+  </style>
+</head>
+  <body>
+    <div id="d" style="background:blue"></div>
+
+  <script type="application/javascript">
+    "use strict";
+
+    var referenceSnapshot;
+    var iterations = 0;
+
+    SimpleTest.waitForExplicitFinish();
+    SimpleTest.requestFlakyTimeout("untriaged");
+
+    function pollForTestPass() {
+      var snapshot = snapshotWindow(window);
+      if (compareSnapshots(referenceSnapshot, snapshot, true)[0]) {
+        ok(true, "Test passed after " + iterations + " iterations");
+        SimpleTest.finish();
+        return;
+      }
+
+      ++iterations;
+      if (iterations == 20) {
+        todo(false, "We couldn't draw the frame, but at least we didn't crash");
+        SimpleTest.finish();
+        return;
+      }
+      setTimeout(pollForTestPass, 10);
+    }
+    function addRemoteFrame() {
+      let iframe = document.createElement("iframe");
+      SpecialPowers.wrap(iframe).mozbrowser = true;
+      iframe.src = "data:text/html,<html style='background:blue;'>";
+
+      document.body.appendChild(iframe);
+
+      pollForTestPass();
+    }
+    addEventListener("load", function() {
+      referenceSnapshot = snapshotWindow(window);
+      document.getElementById("d").style.display = 'none';
+      SpecialPowers.addPermission("browser", true, document);
+      SpecialPowers.pushPrefEnv({
+        "set": [
+          ["dom.ipc.browser_frames.oop_by_default", true],
+          ["dom.mozBrowserFramesEnabled", true]
+        ]
+      }, addRemoteFrame);      
+    });
+  </script>
+</body>
diff --git a/testing/marionette/harness/marionette_harness/tests/unit/test_getactiveframe_oop.py b/testing/marionette/harness/marionette_harness/tests/unit/test_getactiveframe_oop.py
new file mode 100644
index 000000000000..0bfdf017cc34
--- /dev/null
+++ b/testing/marionette/harness/marionette_harness/tests/unit/test_getactiveframe_oop.py
@@ -0,0 +1,95 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+from __future__ import absolute_import
+
+from marionette_driver.by import By
+
+from marionette_harness import MarionetteTestCase
+
+
+OOP_BY_DEFAULT = "dom.ipc.browser_frames.oop_by_default"
+BROWSER_FRAMES_ENABLED = "dom.mozBrowserFramesEnabeld"
+
+
+class TestGetActiveFrameOOP(MarionetteTestCase):
+    def setUp(self):
+        super(TestGetActiveFrameOOP, self).setUp()
+        with self.marionette.using_context("chrome"):
+            self.oop_by_default = self.marionette.get_pref(OOP_BY_DEFAULT)
+            self.mozBrowserFramesEnabled = self.marionette.get_pref(BROWSER_FRAMES_ENABLED)
+            self.marionette.set_pref(OOP_BY_DEFAULT, True)
+            self.marionette.set_pref(BROWSER_FRAMES_ENABLED, True)
+
+    def tearDown(self):
+        with self.marionette.using_context("chrome"):
+            if self.oop_by_default is None:
+                self.marionette.clear_pref(OOP_BY_DEFAULT)
+            else:
+                self.marionette.set_pref(OOP_BY_DEFAULT, self.oop_by_default)
+
+            if self.mozBrowserFramesEnabled is None:
+                self.marionette.clear_pref(BROWSER_FRAMES_ENABLED)
+            else:
+                self.marionette.set_pref(BROWSER_FRAMES_ENABLED, self.mozBrowserFramesEnabled)
+
+    def test_active_frame_oop(self):
+        self.marionette.navigate(self.marionette.absolute_url("test.html"))
+        self.marionette.push_permission('browser', True)
+
+        # Create first OOP frame
+        self.marionette.execute_script("""
+            let iframe1 = document.createElement("iframe");
+            iframe1.id = "remote_iframe1";
+            iframe1.setAttribute('remote', true);
+            iframe1.setAttribute('mozbrowser', true);
+            iframe1.style.height = "100px";
+            iframe1.style.width = "100%%";
+            iframe1.src = "{}";
+            document.body.appendChild(iframe1);
+            """.format(self.marionette.absolute_url("test_oop_1.html")))
+
+        # Currently no active frame
+        self.assertEqual(self.marionette.get_active_frame(), None)
+        self.assertTrue("test.html" in self.marionette.get_url())
+
+        # Switch to iframe1, get active frame
+        frame = self.marionette.find_element(By.ID, 'remote_iframe1')
+        self.marionette.switch_to_frame(frame)
+        active_frame1 = self.marionette.get_active_frame()
+        self.assertNotEqual(active_frame1.id, None)
+
+        # Switch to top-level then back to active frame, verify correct frame
+        self.marionette.switch_to_frame()
+        self.marionette.switch_to_frame(active_frame1)
+        self.assertTrue("test_oop_1.html" in self.marionette.execute_script("return document.wrappedJSObject.location.href"))
+
+        # Create another OOP frame
+        self.marionette.switch_to_frame()
+        self.marionette.execute_script("""
+            let iframe2 = document.createElement("iframe");
+            iframe2.setAttribute('mozbrowser', true);
+            iframe2.setAttribute('remote', true);
+            iframe2.id = "remote_iframe2";
+            iframe2.style.height = "100px";
+            iframe2.style.width = "100%%";
+            iframe2.src = "{}";
+            document.body.appendChild(iframe2);
+            """.format(self.marionette.absolute_url("test_oop_2.html")))
+
+        # Switch to iframe2, get active frame
+        frame2 = self.marionette.find_element(By.ID, 'remote_iframe2')
+        self.marionette.switch_to_frame(frame2)
+        active_frame2 = self.marionette.get_active_frame()
+        self.assertNotEqual(active_frame2.id, None)
+
+        # Switch to top-level then back to active frame 1, verify correct frame
+        self.marionette.switch_to_frame()
+        self.marionette.switch_to_frame(active_frame1)
+        self.assertTrue("test_oop_1.html" in self.marionette.execute_script("return document.wrappedJSObject.location.href"))
+
+        # Switch to top-level then back to active frame 2, verify correct frame
+        self.marionette.switch_to_frame()
+        self.marionette.switch_to_frame(active_frame2)
+        self.assertTrue("test_oop_2.html" in self.marionette.execute_script("return document.wrappedJSObject.location.href"))
diff --git a/testing/marionette/harness/marionette_harness/tests/unit/unit-tests.ini b/testing/marionette/harness/marionette_harness/tests/unit/unit-tests.ini
index 13b4efa79620..b7bd9be75858 100644
--- a/testing/marionette/harness/marionette_harness/tests/unit/unit-tests.ini
+++ b/testing/marionette/harness/marionette_harness/tests/unit/unit-tests.ini
@@ -61,6 +61,8 @@ expected = fail
 [test_wait.py]
 [test_expected.py]
 [test_date_time_value.py]
+[test_getactiveframe_oop.py]
+skip-if = true # Bug 925688
 [test_screen_orientation.py]
 [test_errors.py]
 
diff --git a/testing/specialpowers/content/MockFilePicker.jsm b/testing/specialpowers/content/MockFilePicker.jsm
index 1dd301ccaeb1..4f044998c851 100644
--- a/testing/specialpowers/content/MockFilePicker.jsm
+++ b/testing/specialpowers/content/MockFilePicker.jsm
@@ -17,10 +17,7 @@ const { Services } = ChromeUtils.import("resource://gre/modules/Services.jsm");
 
 // Allow stuff from this scope to be accessed from non-privileged scopes. This
 // would crash if used outside of automation.
-/* globals __URI__ */
-if (__URI__.includes("specialpowers")) {
-  Cu.forcePermissiveCOWs();
-}
+Cu.forcePermissiveCOWs();
 
 var registrar = Cm.QueryInterface(Ci.nsIComponentRegistrar);
 var oldClassID;
diff --git a/testing/specialpowers/content/SpecialPowersChild.jsm b/testing/specialpowers/content/SpecialPowersChild.jsm
index 54421e39f2a0..cea021da4ee5 100644
--- a/testing/specialpowers/content/SpecialPowersChild.jsm
+++ b/testing/specialpowers/content/SpecialPowersChild.jsm
@@ -1864,6 +1864,13 @@ class SpecialPowersChild extends JSWindowActorChild {
     return debugsvc.assertionCount;
   }
 
+  /**
+   * Get the message manager associated with an <iframe mozbrowser>.
+   */
+  getBrowserFrameMessageManager(aFrameElement) {
+    return this.wrap(aFrameElement.frameLoader.messageManager);
+  }
+
   _getPrincipalFromArg(arg) {
     let principal;
     let secMan = Services.scriptSecurityManager;
diff --git a/testing/specialpowers/content/SpecialPowersParent.jsm b/testing/specialpowers/content/SpecialPowersParent.jsm
index 266020c20e18..32268a3f1ba2 100644
--- a/testing/specialpowers/content/SpecialPowersParent.jsm
+++ b/testing/specialpowers/content/SpecialPowersParent.jsm
@@ -71,55 +71,6 @@ function doPrefEnvOp(fn) {
   }
 }
 
-async function createWindowlessBrowser({ isPrivate = false } = {}) {
-  const {
-    promiseDocumentLoaded,
-    promiseEvent,
-    promiseObserved,
-  } = ChromeUtils.import(
-    "resource://gre/modules/ExtensionUtils.jsm"
-  ).ExtensionUtils;
-
-  let windowlessBrowser = Services.appShell.createWindowlessBrowser(true);
-
-  if (isPrivate) {
-    let loadContext = windowlessBrowser.docShell.QueryInterface(
-      Ci.nsILoadContext
-    );
-    loadContext.usePrivateBrowsing = true;
-  }
-
-  let chromeShell = windowlessBrowser.docShell.QueryInterface(
-    Ci.nsIWebNavigation
-  );
-
-  const system = Services.scriptSecurityManager.getSystemPrincipal();
-  chromeShell.createAboutBlankContentViewer(system, system);
-  chromeShell.useGlobalHistory = false;
-  chromeShell.loadURI("chrome://extensions/content/dummy.xhtml", {
-    triggeringPrincipal: system,
-  });
-
-  await promiseObserved(
-    "chrome-document-global-created",
-    win => win.document == chromeShell.document
-  );
-
-  let chromeDoc = await promiseDocumentLoaded(chromeShell.document);
-
-  let browser = chromeDoc.createXULElement("browser");
-  browser.setAttribute("type", "content");
-  browser.setAttribute("disableglobalhistory", "true");
-  browser.setAttribute("remote", "true");
-
-  let promise = promiseEvent(browser, "XULFrameLoaderCreated");
-  chromeDoc.documentElement.appendChild(browser);
-
-  await promise;
-
-  return { windowlessBrowser, browser };
-}
-
 // Supplies the unique IDs for tasks created by SpecialPowers.spawn(),
 // used to bounce assertion messages back down to the correct child.
 let nextTaskID = 1;
@@ -870,7 +821,6 @@ class SpecialPowersParent extends JSWindowActorParent {
         );
 
         Object.assign(sb.sandbox, {
-          createWindowlessBrowser,
           sendAsyncMessage: (name, message) => {
             this.sendAsyncMessage("SPChromeScriptMessage", {
               id,
diff --git a/testing/specialpowers/content/SpecialPowersSandbox.jsm b/testing/specialpowers/content/SpecialPowersSandbox.jsm
index b5a2fe46ab63..97a2924bb485 100644
--- a/testing/specialpowers/content/SpecialPowersSandbox.jsm
+++ b/testing/specialpowers/content/SpecialPowersSandbox.jsm
@@ -24,7 +24,6 @@ ChromeUtils.defineModuleGetter(
 const SANDBOX_GLOBALS = [
   "Blob",
   "ChromeUtils",
-  "FileReader",
   "TextDecoder",
   "TextEncoder",
   "URL",
diff --git a/testing/specialpowers/moz.build b/testing/specialpowers/moz.build
index 96c2912bdd16..e7047bf5a4fa 100644
--- a/testing/specialpowers/moz.build
+++ b/testing/specialpowers/moz.build
@@ -26,9 +26,5 @@ FINAL_TARGET_FILES.content += [
     'content/WrapPrivileged.jsm',
 ]
 
-TESTING_JS_MODULES += [
-    'content/MockFilePicker.jsm',
-]
-
 with Files("**"):
     BUG_COMPONENT = ("Testing", "Mochitest")
diff --git a/toolkit/components/contentprefs/tests/mochitest/mochitest.ini b/toolkit/components/contentprefs/tests/mochitest/mochitest.ini
index 1431acaa9ac0..bef1e541defb 100644
--- a/toolkit/components/contentprefs/tests/mochitest/mochitest.ini
+++ b/toolkit/components/contentprefs/tests/mochitest/mochitest.ini
@@ -1,3 +1,4 @@
 [DEFAULT]
 
 [test_remoteContentPrefs.html]
+skip-if = e10s # bug 783513
diff --git a/toolkit/components/contentprefs/tests/mochitest/test_remoteContentPrefs.html b/toolkit/components/contentprefs/tests/mochitest/test_remoteContentPrefs.html
index cb57e577cdc4..2de831d989b4 100644
--- a/toolkit/components/contentprefs/tests/mochitest/test_remoteContentPrefs.html
+++ b/toolkit/components/contentprefs/tests/mochitest/test_remoteContentPrefs.html
@@ -11,328 +11,339 @@
   <script type="application/javascript">
     "use strict";
 
-    async function chromeScriptFunc() {
-      let loadContext = Cu.createLoadContext();
-      let privateLoadContext = Cu.createPrivateLoadContext();
+    let Cu = SpecialPowers.Cu;
+    let loadContext = Cu.createLoadContext();
+    let privateLoadContext = Cu.createPrivateLoadContext();
 
-      const childFrameURL =
-        "data:text/html,<!DOCTYPE HTML><html><body></body></html>";
+    SimpleTest.waitForExplicitFinish();
 
-      function childFrameScript(isFramePrivate) {
-        "use strict";
-        /* global addMessageListener */
+    const childFrameURL =
+      "data:text/html,<!DOCTYPE HTML><html><body></body></html>";
 
-        dump("Hallo am child.\n")
-
-        /* eslint no-shadow: 0 */
-        function Defer() {
-          let d = {};
-          d.promise = new Promise((resolve, reject) => {
-            d.resolve = resolve;
-            d.reject = reject;
-          });
-
-          return d;
-        }
-
-        function Tester(mm) {
-          this.mm = mm;
-        }
-
-        Tester.prototype.is =
-          function(a, b, note) {
-            this.mm.sendAsyncMessage("testRemoteContentPrefs:ok", { test: [a === b, note + " (" + a + ", " + b + ")"] });
-          };
-        Tester.prototype.ok =
-          function(b, note) {
-            this.mm.sendAsyncMessage("testRemoteContentPrefs:ok", { test: [!!b, note] });
-          };
-        Tester.prototype.info =
-          function(note) {
-            this.mm.sendAsyncMessage("testRemoteContentPrefs:info", { note });
-          };
-
-        var cps = Cc["@mozilla.org/content-pref/service;1"]
-                    .getService(Ci.nsIContentPrefService2);
-
-        async function test1(mm) {
-          let tester = new Tester(mm);
-
-          tester.ok(cps !== null, "got the content pref service");
-
-          let setPref = Defer();
-          cps.setGlobal("testing", 42, null, {
-            handleCompletion(reason) {
-              tester.is(reason, 0, "set a pref?");
-              setPref.resolve();
-            },
-          });
-
-          await setPref.promise;
-
-          let numResults = 0;
-          let gotGlobal = Defer();
-          cps.getGlobal("testing", null, {
-            handleResult(pref) {
-              numResults++;
-              tester.is(pref.name, "testing", "pref has the right name");
-              tester.is(pref.value, 42, "pref has the right value");
-            },
-
-            handleCompletion(reason) {
-              tester.is(reason, 0, "get a pref?");
-              tester.is(numResults, 1, "got the right number of prefs");
-              gotGlobal.resolve();
-            },
-          });
-
-          await gotGlobal.promise;
-        }
-
-        async function test2(mm) {
-          let tester = new Tester(mm);
-
-          let observer;
-          let removed = false;
-          let gotSet = Defer();
-          let gotRemoved = Defer();
-          cps.addObserverForName("testName", observer = {
-            onContentPrefSet(group, name, value, isPrivate) {
-              tester.info("received prefSet notification");
-              if (removed) {
-                mm.sendAsyncMessage("testRemoteContentPrefs:fail",
-                                    { reason: "unexpected notification" });
-              }
-              tester.is(group, null, "group should be null");
-              tester.is(name, "testName", "should only see testName");
-              tester.is(value, 42, "value should be correct");
-              tester.is(isPrivate, isFramePrivate, "privacy should match");
-
-              gotSet.resolve();
-            },
-
-            onContentPrefRemoved(group, name, isPrivate) {
-              tester.info("received prefRemoved notification");
-              tester.is(group, null, "group should be null");
-              tester.is(name, "testName", "name should match");
-              tester.is(isPrivate, isFramePrivate, "privacy should match");
-
-              cps.removeObserverForName("testName", observer);
-              removed = true;
-
-              gotRemoved.resolve();
-            },
-          });
-
-          mm.sendAsyncMessage("testRemoteContentPrefs:test2poke", {});
-          await gotSet.promise;
-
-          mm.sendAsyncMessage("testRemoteContentPrefs:test2poke2", {});
-          await gotRemoved.promise;
-        }
-
-        async function test3(mm) {
-          let tester = new Tester(mm);
-
-          let setGlobalDone = Defer();
-          cps.setGlobal("testName", 42, null, {
-            handleCompletion(reason) {
-              tester.is(reason, 0, "set a pref");
-              cps.set("http://mochi.test", "testpref", "str", null, {
-                /* eslint no-shadow: 0 */
-                handleCompletion(reason) {
-                  tester.is(reason, 0, "set a pref");
-                  setGlobalDone.resolve();
-                },
-              });
-            },
-          });
-
-          await setGlobalDone.promise;
-
-          let removeDone = Defer();
-          cps.removeByDomain("http://mochi.test", null, {
-            handleCompletion(reason) {
-              tester.is(reason, 0, "remove succeeded");
-              cps.getByDomainAndName("http://mochi.test", "testpref", null, {
-                handleResult() {
-                  mm.sendAsyncMessage("testRemoteContentPrefs:fail",
-                                      { reason: "got removed pref in test3" });
-                },
-                handleCompletion() {
-                  removeDone.resolve();
-                },
-                handleError(rv) {
-                  mm.sendAsyncMessage("testRemoteContentPrefs:fail",
-                                      { reason: `got a pref error ${rv}` });
-                },
-              });
-            },
-          });
-
-          await removeDone.promise;
-        }
-
-        async function test4(mm) {
-          let tester = new Tester(mm);
-
-          let observed = Defer();
-          let prefObserver = {
-            onContentPrefSet(group, name, value, isPrivate) {
-              observed.resolve({ group, name, value, isPrivate });
-            },
-            onContentPrefRemoved(group, name, isPrivate) {
-              observed.reject("got unexpected notification");
-            },
-          };
-
-          cps.addObserverForName("test", prefObserver);
-
-          let privateLoadContext = Cu.createPrivateLoadContext();
-          cps.set("http://mochi.test", "test", 42, privateLoadContext);
-          let event = await observed.promise;
-          tester.is(event.name, "test", "got the right event");
-          tester.is(event.isPrivate, true, "the event was for an isPrivate pref");
-
-          mm.sendAsyncMessage("testRemoteContentPrefs:getPref",
-                              { group: "http://mochi.test", name: "test" });
-
-          let results = await new Promise(resolve => {
-            addMessageListener("testRemoteContentPrefs:prefResults",
-                               (msg) => { resolve(msg.data.results); });
-          });
-          tester.is(results.length, 0, "should not have seen the pb pref");
-        }
-
-        var tests = { test1, test2, test3, test4 };
-        function testHandler(mm, testName) {
-          tests[testName](mm).then(() => {
-            mm.sendAsyncMessage(`testRemoteContentPrefs:${testName}Finished`, {});
-          }).catch((e) => {
-            mm.sendAsyncMessage("testRemoteContentPrefs:fail", { reason: e });
-          });
-        }
-
-        for (let test of Object.getOwnPropertyNames(tests)) {
-          addMessageListener(`testRemoteContentPrefs:${test}`, function(message) {
-            dump("Hallo am child message.\n")
-            testHandler(message.target, test);
-          });
-        }
-      }
+    function childFrameScript(isFramePrivate) {
+      "use strict";
+      /* global addMessageListener */
 
+      /* eslint no-shadow: 0 */
       function Defer() {
-        var d = {};
+        let d = {};
         d.promise = new Promise((resolve, reject) => {
           d.resolve = resolve;
           d.reject = reject;
         });
+
         return d;
       }
 
-      async function testStructure(mm, isPrivate) {
-        var curTest;
-        function testDone(msg) {
-          info(`in testDone ${msg.name}`);
-          curTest.resolve();
+      function Tester(mm) {
+        this.mm = mm;
+      }
+
+      Tester.prototype.is =
+        function(a, b, note) {
+          this.mm.sendAsyncMessage("testRemoteContentPrefs:ok", { test: [a === b, note + " (" + a + ", " + b + ")"] });
+        };
+      Tester.prototype.ok =
+        function(b, note) {
+          this.mm.sendAsyncMessage("testRemoteContentPrefs:ok", { test: [!!b, note] });
+        };
+      Tester.prototype.info =
+        function(note) {
+          this.mm.sendAsyncMessage("testRemoteContentPrefs:info", { note });
         };
 
-        mm.addMessageListener("testRemoteContentPrefs:test1Finished", testDone);
-        mm.addMessageListener("testRemoteContentPrefs:test2Finished", testDone);
-        mm.addMessageListener("testRemoteContentPrefs:test3Finished", testDone);
-        mm.addMessageListener("testRemoteContentPrefs:test4Finished", testDone);
+      var cps = Cc["@mozilla.org/content-pref/service;1"]
+                  .getService(Ci.nsIContentPrefService2);
 
-        mm.addMessageListener("testRemoteContentPrefs:fail", function(msg) {
-          ok(false, msg.data.reason);
-          SimpleTest.finish();
+      async function test1(mm) {
+        let tester = new Tester(mm);
+
+        tester.ok(cps !== null, "got the content pref service");
+
+        let setPref = Defer();
+        cps.setGlobal("testing", 42, null, {
+          handleCompletion(reason) {
+            tester.is(reason, 0, "set a pref?");
+            setPref.resolve();
+          },
         });
 
-        mm.addMessageListener("testRemoteContentPrefs:ok", (msg) => {
-          let test = msg.data.test;
-          ok(...test);
-        });
-        mm.addMessageListener("testRemoteContentPrefs:info", (msg) => {
-          info(msg.data.note);
+        await setPref.promise;
+
+        let numResults = 0;
+        let gotGlobal = Defer();
+        cps.getGlobal("testing", null, {
+          handleResult(pref) {
+            numResults++;
+            tester.is(pref.name, "testing", "pref has the right name");
+            tester.is(pref.value, 42, "pref has the right value");
+          },
+
+          handleCompletion(reason) {
+            tester.is(reason, 0, "get a pref?");
+            tester.is(numResults, 1, "got the right number of prefs");
+            gotGlobal.resolve();
+          },
         });
 
-        curTest = Defer();
-        mm.sendAsyncMessage("testRemoteContentPrefs:test1", {});
-        await curTest.promise;
-
-        curTest = Defer();
-        var cps = Cc["@mozilla.org/content-pref/service;1"]
-          .getService(Ci.nsIContentPrefService2);
-        mm.addMessageListener("testRemoteContentPrefs:test2poke", function() {
-          info(`received test2poke isPrivate: ${isPrivate}`);
-          cps.setGlobal("testName", 42, isPrivate ? privateLoadContext : loadContext);
-        });
-        mm.addMessageListener("testRemoteContentPrefs:test2poke2", function() {
-          info(`received test2poke2 isPrivate: ${isPrivate}`);
-          cps.removeGlobal("testName", isPrivate ? privateLoadContext : loadContext);
-        });
-        mm.sendAsyncMessage("testRemoteContentPrefs:test2", {});
-        await curTest.promise;
-
-        curTest = Defer();
-        mm.sendAsyncMessage("testRemoteContentPrefs:test3", {});
-        await curTest.promise;
-
-        curTest = Defer();
-        mm.addMessageListener("testRemoteContentPrefs:getPref", function(msg) {
-          let results = [];
-          cps.getByDomainAndName(msg.data.group, msg.data.name, null, {
-            handleResult(pref) {
-              info("received handleResult");
-              results.push(pref);
-            },
-            handleCompletion(reason) {
-              mm.sendAsyncMessage("testRemoteContentPrefs:prefResults",
-                                  { results });
-            },
-            handleError(rv) {
-              ok(false, `failed to get pref ${rv}`);
-              curTest.reject("got unexpected error");
-            },
-          });
-        });
-
-        mm.sendAsyncMessage("testRemoteContentPrefs:test4", {});
-        await curTest.promise;
+        await gotGlobal.promise;
       }
 
-      async function runTest(isPrivate) {
-        /* globals Services, createWindowlessBrowser */
-        info("testing with isPrivate=" + isPrivate);
-        let { windowlessBrowser, browser } = await createWindowlessBrowser({ isPrivate });
+      async function test2(mm) {
+        let tester = new Tester(mm);
 
-        const system = Services.scriptSecurityManager.getSystemPrincipal();
+        let observer;
+        let removed = false;
+        let gotSet = Defer();
+        let gotRemoved = Defer();
+        cps.addObserverForName("testName", observer = {
+          onContentPrefSet(group, name, value, isPrivate) {
+            tester.info("received prefSet notification");
+            if (removed) {
+              mm.sendAsyncMessage("testRemoteContentPrefs:fail",
+                                  { reason: "unexpected notification" });
+            }
+            tester.is(group, null, "group should be null");
+            tester.is(name, "testName", "should only see testName");
+            tester.is(value, 42, "value should be correct");
+            tester.is(isPrivate, isFramePrivate, "privacy should match");
 
-        browser.loadURI(childFrameURL, { triggeringPrincipal: system });
+            gotSet.resolve();
+          },
 
-        let mm = browser.messageManager;
-        mm.loadFrameScript(`data:,` + encodeURI(`(${childFrameScript})(${isPrivate})`),
-                           false);
+          onContentPrefRemoved(group, name, isPrivate) {
+            tester.info("received prefRemoved notification");
+            tester.is(group, null, "group should be null");
+            tester.is(name, "testName", "name should match");
+            tester.is(isPrivate, isFramePrivate, "privacy should match");
 
-        await testStructure(mm, isPrivate);
+            cps.removeObserverForName("testName", observer);
+            removed = true;
 
-        windowlessBrowser.close();
+            gotRemoved.resolve();
+          },
+        });
+
+        mm.sendAsyncMessage("testRemoteContentPrefs:test2poke", {});
+        await gotSet.promise;
+
+        mm.sendAsyncMessage("testRemoteContentPrefs:test2poke2", {});
+        await gotRemoved.promise;
       }
 
-      try {
-        await runTest(false);
-        await runTest(true);
-      } catch (e) {
-        Cu.reportError(e);
-        ok(false, "Test task threw exception");
+      async function test3(mm) {
+        let tester = new Tester(mm);
+
+        let setGlobalDone = Defer();
+        cps.setGlobal("testName", 42, null, {
+          handleCompletion(reason) {
+            tester.is(reason, 0, "set a pref");
+            cps.set("http://mochi.test", "testpref", "str", null, {
+              /* eslint no-shadow: 0 */
+              handleCompletion(reason) {
+                tester.is(reason, 0, "set a pref");
+                setGlobalDone.resolve();
+              },
+            });
+          },
+        });
+
+        await setGlobalDone.promise;
+
+        let removeDone = Defer();
+        cps.removeByDomain("http://mochi.test", null, {
+          handleCompletion(reason) {
+            tester.is(reason, 0, "remove succeeded");
+            cps.getByDomainAndName("http://mochi.test", "testpref", null, {
+              handleResult() {
+                mm.sendAsyncMessage("testRemoteContentPrefs:fail",
+                                    { reason: "got removed pref in test3" });
+              },
+              handleCompletion() {
+                removeDone.resolve();
+              },
+              handleError(rv) {
+                mm.sendAsyncMessage("testRemoteContentPrefs:fail",
+                                    { reason: `got a pref error ${rv}` });
+              },
+            });
+          },
+        });
+
+        await removeDone.promise;
+      }
+
+      async function test4(mm) {
+        let tester = new Tester(mm);
+
+        let observed = Defer();
+        let prefObserver = {
+          onContentPrefSet(group, name, value, isPrivate) {
+            observed.resolve({ group, name, value, isPrivate });
+          },
+          onContentPrefRemoved(group, name, isPrivate) {
+            observed.reject("got unexpected notification");
+          },
+        };
+
+        cps.addObserverForName("test", prefObserver);
+
+        let privateLoadContext = Cu.createPrivateLoadContext();
+        cps.set("http://mochi.test", "test", 42, privateLoadContext);
+        let event = await observed.promise;
+        tester.is(event.name, "test", "got the right event");
+        tester.is(event.isPrivate, true, "the event was for an isPrivate pref");
+
+        mm.sendAsyncMessage("testRemoteContentPrefs:getPref",
+                            { group: "http://mochi.test", name: "test" });
+
+        let results = await new Promise(resolve => {
+          addMessageListener("testRemoteContentPrefs:prefResults",
+                             (msg) => { resolve(msg.data.results); });
+        });
+        tester.is(results.length, 0, "should not have seen the pb pref");
+      }
+
+      var tests = { test1, test2, test3, test4 };
+      function testHandler(mm, testName) {
+        tests[testName](mm).then(() => {
+          mm.sendAsyncMessage(`testRemoteContentPrefs:${testName}Finished`, {});
+        }).catch((e) => {
+          mm.sendAsyncMessage("testRemoteContentPrefs:fail", { reason: e });
+        });
+      }
+
+      for (let test of Object.getOwnPropertyNames(tests)) {
+        addMessageListener(`testRemoteContentPrefs:${test}`, function(message) {
+          testHandler(message.target, test);
+        });
       }
-      /* globals sendAsyncMessage */
-      sendAsyncMessage("done");
     }
 
-    add_task(async function() {
-      let chromeScript = SpecialPowers.loadChromeScript(chromeScriptFunc);
-      await chromeScript.promiseOneMessage("done");
-      await chromeScript.destroy();
+    function Defer() {
+      var d = {};
+      d.promise = new Promise((resolve, reject) => {
+        d.resolve = resolve;
+        d.reject = reject;
+      });
+      return d;
+    }
+
+    async function testStructure(mm, isPrivate) {
+      var curTest;
+      var testDone = SpecialPowers.wrapCallback(function testDone(msg) {
+        info(`in testDone ${msg.name}`);
+        curTest.resolve();
+      });
+
+      mm.addMessageListener("testRemoteContentPrefs:test1Finished", testDone);
+      mm.addMessageListener("testRemoteContentPrefs:test2Finished", testDone);
+      mm.addMessageListener("testRemoteContentPrefs:test3Finished", testDone);
+      mm.addMessageListener("testRemoteContentPrefs:test4Finished", testDone);
+
+      mm.addMessageListener("testRemoteContentPrefs:fail", SpecialPowers.wrapCallback(function(msg) {
+        ok(false, msg.data.reason);
+        SimpleTest.finish();
+      }));
+
+      mm.addMessageListener("testRemoteContentPrefs:ok", SpecialPowers.wrapCallback((msg) => {
+        let test = msg.data.test;
+        ok(...test);
+      }));
+      mm.addMessageListener("testRemoteContentPrefs:info", SpecialPowers.wrapCallback((msg) => {
+        info(msg.data.note);
+      }));
+
+      curTest = Defer();
+      mm.sendAsyncMessage("testRemoteContentPrefs:test1", {});
+      await curTest.promise;
+
+      curTest = Defer();
+      var cps = SpecialPowers.Cc["@mozilla.org/content-pref/service;1"]
+                             .getService(SpecialPowers.Ci.nsIContentPrefService2);
+      mm.addMessageListener("testRemoteContentPrefs:test2poke", function() {
+        info(`received test2poke isPrivate: ${isPrivate}`);
+        cps.setGlobal("testName", 42, isPrivate ? privateLoadContext : loadContext);
+      });
+      mm.addMessageListener("testRemoteContentPrefs:test2poke2", function() {
+        info(`received test2poke2 isPrivate: ${isPrivate}`);
+        cps.removeGlobal("testName", isPrivate ? privateLoadContext : loadContext);
+      });
+      mm.sendAsyncMessage("testRemoteContentPrefs:test2", {});
+      await curTest.promise;
+
+      curTest = Defer();
+      mm.sendAsyncMessage("testRemoteContentPrefs:test3", {});
+      await curTest.promise;
+
+      curTest = Defer();
+      mm.addMessageListener("testRemoteContentPrefs:getPref", SpecialPowers.wrapCallback(function(msg) {
+        let results = [];
+        cps.getByDomainAndName(msg.data.group, msg.data.name, null, {
+          handleResult(pref) {
+            info("received handleResult");
+            results.push(pref);
+          },
+          handleCompletion(reason) {
+            mm.sendAsyncMessage("testRemoteContentPrefs:prefResults",
+                                { results });
+          },
+          handleError(rv) {
+            ok(false, `failed to get pref ${rv}`);
+            curTest.reject("got unexpected error");
+          },
+        });
+      }));
+
+      mm.sendAsyncMessage("testRemoteContentPrefs:test4", {});
+      await curTest.promise;
+
+      document.getElementById("iframe").remove();
+    }
+
+    function runTest(isPrivate) {
+      info("testing with isPrivate=" + isPrivate);
+      let iframe = document.createElement("iframe");
+      SpecialPowers.wrap(iframe).mozbrowser = true;
+      if (isPrivate) {
+        SpecialPowers.wrap(iframe).mozprivatebrowsing = true;
+      }
+      iframe.id = "iframe";
+      iframe.src = childFrameURL;
+
+      let deferred = Defer();
+      iframe.addEventListener("mozbrowserloadend", function() {
+        info("Got iframe load event.");
+        let mm = SpecialPowers.getBrowserFrameMessageManager(iframe);
+        mm.loadFrameScript("data:,(" + childFrameScript.toString() + ")(" + isPrivate + ");",
+                           false);
+
+        // Chain testStructure to runTests's promise.
+        testStructure(mm, isPrivate).then(deferred.resolve)
+                                    .catch((e) => { info(`caught failing test ${e}`); });
+      });
+
+      document.body.appendChild(iframe);
+      return deferred.promise;
+    }
+
+    function runTests() {
+      info("Browser prefs set.");
+      add_task(() => { return runTest(false); });
+      add_task(() => { return runTest(true); });
+    }
+
+    addEventListener("load", function() {
+      info("Got load event.");
+
+      SpecialPowers.addPermission("browser", true, document);
+      SpecialPowers.pushPrefEnv({
+        "set": [
+          ["dom.ipc.browser_frames.oop_by_default", true],
+          ["dom.mozBrowserFramesEnabled", true],
+          ["browser.pagethumbnails.capturing_disabled", true],
+        ],
+      }, runTests);
     });
   </script>
 </body>
diff --git a/toolkit/components/windowwatcher/nsWindowWatcher.cpp b/toolkit/components/windowwatcher/nsWindowWatcher.cpp
index 2f6825bd0b40..c174643a37a2 100644
--- a/toolkit/components/windowwatcher/nsWindowWatcher.cpp
+++ b/toolkit/components/windowwatcher/nsWindowWatcher.cpp
@@ -1980,6 +1980,13 @@ uint32_t nsWindowWatcher::CalculateChromeFlagsForParent(
     chromeFlags = EnsureFlagsSafeForContent(chromeFlags, aChromeURL);
   }
 
+  // Disable CHROME_OPENAS_DIALOG if the window is inside <iframe mozbrowser>.
+  // It's up to the embedder to interpret what dialog=1 means.
+  nsCOMPtr<nsIDocShell> docshell = do_GetInterface(aParent);
+  if (docshell && docshell->GetIsInMozBrowser()) {
+    chromeFlags &= ~nsIWebBrowserChrome::CHROME_OPENAS_DIALOG;
+  }
+
   return chromeFlags;
 }
 
diff --git a/toolkit/content/tests/browser/browser_content_url_annotation.js b/toolkit/content/tests/browser/browser_content_url_annotation.js
index 72180ec2d060..7e4887b40e85 100644
--- a/toolkit/content/tests/browser/browser_content_url_annotation.js
+++ b/toolkit/content/tests/browser/browser_content_url_annotation.js
@@ -1,7 +1,7 @@
 /* Any copyright is dedicated to the Public Domain.
  * http://creativecommons.org/publicdomain/zero/1.0/ */
 /* global Services, requestLongerTimeout, TestUtils, BrowserTestUtils,
- ok, info, dump, is, Ci, Cu, Components, ctypes,
+ ok, info, dump, is, Ci, Cu, Components, ctypes, privateNoteIntentionalCrash,
  gBrowser, add_task, addEventListener, removeEventListener, ContentTask */
 
 "use strict";
diff --git a/tools/lint/eslint/eslint-plugin-mozilla/lib/configs/browser-test.js b/tools/lint/eslint/eslint-plugin-mozilla/lib/configs/browser-test.js
index 596815c85020..e78c6f0b6641 100644
--- a/tools/lint/eslint/eslint-plugin-mozilla/lib/configs/browser-test.js
+++ b/tools/lint/eslint/eslint-plugin-mozilla/lib/configs/browser-test.js
@@ -41,6 +41,7 @@ module.exports = {
     is: false,
     isnot: false,
     ok: false,
+    privateNoteIntentionalCrash: false,
     record: false,
     registerCleanupFunction: false,
     requestLongerTimeout: false,
diff --git a/tools/lint/eslint/eslint-plugin-mozilla/lib/environments/frame-script.js b/tools/lint/eslint/eslint-plugin-mozilla/lib/environments/frame-script.js
index 5c80dd792138..f90292204a1d 100644
--- a/tools/lint/eslint/eslint-plugin-mozilla/lib/environments/frame-script.js
+++ b/tools/lint/eslint/eslint-plugin-mozilla/lib/environments/frame-script.js
@@ -17,6 +17,7 @@ module.exports = {
     chromeOuterWindowID: false,
     content: false,
     docShell: false,
+    privateNoteIntentionalCrash: false,
     processMessageManager: false,
     removeMessageListener: false,
     removeWeakMessageListener: false,