diff --git a/browser/base/content/test/general/browser_gZipOfflineChild.js b/browser/base/content/test/general/browser_gZipOfflineChild.js
index 5312e8a9b5a8..d21e338c03ca 100644
--- a/browser/base/content/test/general/browser_gZipOfflineChild.js
+++ b/browser/base/content/test/general/browser_gZipOfflineChild.js
@@ -18,6 +18,8 @@ registerCleanupFunction(function() {
 // offline cache events.
 //
 function contentTask() {
+  ChromeUtils.import("resource://gre/modules/Timer.jsm");
+
   let resolve;
   let promise = new Promise(r => { resolve = r; });
 
diff --git a/browser/base/content/test/popupNotifications/browser_displayURI.js b/browser/base/content/test/popupNotifications/browser_displayURI.js
index c27299efb2e7..ebdbaf6cdb4d 100644
--- a/browser/base/content/test/popupNotifications/browser_displayURI.js
+++ b/browser/base/content/test/popupNotifications/browser_displayURI.js
@@ -92,6 +92,7 @@ add_task(async function test_displayURI_camera() {
 
 add_task(async function test_displayURI_geo_blob() {
   await check(async function() {
+    Cu.importGlobalProperties(["Blob"]);
     let text = "<script>navigator.geolocation.getCurrentPosition(() => {})</script>";
     let blob = new Blob([text], {type: "text/html"});
     let url = content.URL.createObjectURL(blob);
@@ -101,6 +102,7 @@ add_task(async function test_displayURI_geo_blob() {
 
 add_task(async function test_displayURI_camera_blob() {
   await check(async function() {
+    Cu.importGlobalProperties(["Blob"]);
     let text = "<script>navigator.mediaDevices.getUserMedia({video: true, fake: true})</script>";
     let blob = new Blob([text], {type: "text/html"});
     let url = content.URL.createObjectURL(blob);
diff --git a/browser/base/content/test/webrtc/get_user_media_content_script.js b/browser/base/content/test/webrtc/get_user_media_content_script.js
index ffb51b94ea39..ede230855d8b 100644
--- a/browser/base/content/test/webrtc/get_user_media_content_script.js
+++ b/browser/base/content/test/webrtc/get_user_media_content_script.js
@@ -3,6 +3,7 @@
 
 /* eslint-env mozilla/frame-script */
 
+ChromeUtils.import("resource://gre/modules/AppConstants.jsm");
 ChromeUtils.import("resource://gre/modules/XPCOMUtils.jsm");
 XPCOMUtils.defineLazyServiceGetter(this, "MediaManagerService",
                                    "@mozilla.org/mediaManagerService;1",
diff --git a/browser/components/newtab/test/browser/browser_topsites_section.js b/browser/components/newtab/test/browser/browser_topsites_section.js
index d6a8b6dae628..e726c1d32ff6 100644
--- a/browser/components/newtab/test/browser/browser_topsites_section.js
+++ b/browser/components/newtab/test/browser/browser_topsites_section.js
@@ -65,7 +65,7 @@ test_newtab({
   // it should be able to click the topsites edit button to reveal the edit topsites modal and overlay.
   test: async function topsites_add() {
     let nativeInputValueSetter = Object.getOwnPropertyDescriptor(content.window.HTMLInputElement.prototype, "value").set;
-    let event = new Event("input", {bubbles: true});
+    let event = new content.Event("input", {bubbles: true});
 
     // Find the add topsites button
     content.document.querySelector(".top-sites .section-top-bar .context-menu-button").click();
diff --git a/browser/components/payments/content/paymentDialogFrameScript.js b/browser/components/payments/content/paymentDialogFrameScript.js
index 3e92bca88f74..2159f4ffad85 100644
--- a/browser/components/payments/content/paymentDialogFrameScript.js
+++ b/browser/components/payments/content/paymentDialogFrameScript.js
@@ -90,12 +90,12 @@ let PaymentFrameScript = {
       },
 
       getDefaultPreferences() {
-        let prefValues = {
+        let prefValues = Cu.cloneInto({
           saveCreditCardDefaultChecked:
             Services.prefs.getBoolPref(SAVE_CREDITCARD_DEFAULT_PREF, false),
           saveAddressDefaultChecked:
             Services.prefs.getBoolPref(SAVE_ADDRESS_DEFAULT_PREF, false),
-        };
+        }, waivedContent);
         return prefValues;
       },
     };
diff --git a/browser/components/uitour/test/head.js b/browser/components/uitour/test/head.js
index 7203ead58f40..b8990ab9b2ef 100644
--- a/browser/components/uitour/test/head.js
+++ b/browser/components/uitour/test/head.js
@@ -323,7 +323,7 @@ function loadUITourTestPage(callback, host = "https://example.org/") {
               let callbacksCalled = 0;
               let resolveCallbackPromise;
               let allCallbacksCalledPromise = new Promise(resolve => resolveCallbackPromise = resolve);
-              let argumentsWithFunctions = contentArgs.args.map((arg, index) => {
+              let argumentsWithFunctions = Cu.cloneInto(contentArgs.args.map((arg, index) => {
                 if (arg === "" && contentArgs.fnIndices.includes(index)) {
                   return function() {
                     callbacksCalled++;
@@ -334,9 +334,9 @@ function loadUITourTestPage(callback, host = "https://example.org/") {
                   };
                 }
                 return arg;
-              });
+              }), content, {cloneFunctions: true});
               let rv = contentWin.Mozilla.UITour[contentArgs.methodName].apply(contentWin.Mozilla.UITour,
-                                                                        argumentsWithFunctions);
+                                                                               argumentsWithFunctions);
               if (contentArgs.fnIndices.length) {
                 await allCallbacksCalledPromise;
               }
diff --git a/devtools/client/debugger/test/mochitest/code_frame-script.js b/devtools/client/debugger/test/mochitest/code_frame-script.js
index da1e9c40d03e..d55bc1db37ea 100644
--- a/devtools/client/debugger/test/mochitest/code_frame-script.js
+++ b/devtools/client/debugger/test/mochitest/code_frame-script.js
@@ -23,7 +23,7 @@ this.call = function (name, args) {
   dump("Calling function with name " + name + ".\n");
 
   dump("args " + JSON.stringify(args) + "\n");
-  return XPCNativeWrapper.unwrap(content)[name].apply(undefined, args);
+  return XPCNativeWrapper.unwrap(content)[name].apply(undefined, Cu.cloneInto(args, content));
 };
 
 this._eval = function (string) {
diff --git a/dom/cache/test/mochitest/browser_cache_pb_window.js b/dom/cache/test/mochitest/browser_cache_pb_window.js
index 09ac5c45df23..8395f81c1a24 100644
--- a/dom/cache/test/mochitest/browser_cache_pb_window.js
+++ b/dom/cache/test/mochitest/browser_cache_pb_window.js
@@ -72,6 +72,8 @@ function testKeys(browser) {
 
 function testOpen_worker(browser) {
   return ContentTask.spawn(browser, {}, function() {
+    Cu.importGlobalProperties(["Blob"]);
+
     let workerFunctionString = function () {
       caches.open("pb-worker-cache").then(function(cacheObject) {
         postMessage(cacheObject.toString());
diff --git a/dom/file/ipc/tests/browser_ipcBlob.js b/dom/file/ipc/tests/browser_ipcBlob.js
index d8b5ac725747..f622a8a6918f 100644
--- a/dom/file/ipc/tests/browser_ipcBlob.js
+++ b/dom/file/ipc/tests/browser_ipcBlob.js
@@ -11,6 +11,7 @@ add_task(async function test_CtoPtoC_big() {
   let browser1 = gBrowser.getBrowserForTab(tab1);
 
   let blob = await ContentTask.spawn(browser1, null, function() {
+    Cu.importGlobalProperties(["Blob"]);
     let blob = new Blob([new Array(1024*1024).join('123456789ABCDEF')]);
     return blob;
   });
@@ -43,6 +44,7 @@ add_task(async function test_CtoPtoC_small() {
   let browser1 = gBrowser.getBrowserForTab(tab1);
 
   let blob = await ContentTask.spawn(browser1, null, function() {
+    Cu.importGlobalProperties(["Blob"]);
     let blob = new Blob(["hello world!"]);
     return blob;
   });
@@ -75,6 +77,7 @@ add_task(async function test_CtoPtoC_bc_big() {
   let browser1 = gBrowser.getBrowserForTab(tab1);
 
   await ContentTask.spawn(browser1, null, function() {
+    Cu.importGlobalProperties(["Blob"]);
     var bc = new content.BroadcastChannel('test');
     bc.onmessage = function() {
       bc.postMessage(new Blob([new Array(1024*1024).join('123456789ABCDEF')]));
@@ -111,6 +114,7 @@ add_task(async function test_CtoPtoC_bc_small() {
   let browser1 = gBrowser.getBrowserForTab(tab1);
 
   await ContentTask.spawn(browser1, null, function() {
+    Cu.importGlobalProperties(["Blob"]);
     var bc = new content.BroadcastChannel('test');
     bc.onmessage = function() {
       bc.postMessage(new Blob(["hello world!"]));
@@ -147,6 +151,7 @@ add_task(async function test_CtoPtoC_bc_small() {
   let browser1 = gBrowser.getBrowserForTab(tab1);
 
   let blobURL = await ContentTask.spawn(browser1, null, function() {
+    Cu.importGlobalProperties(["Blob"]);
     return content.URL.createObjectURL(new content.Blob(["hello world!"]));
   });
 
@@ -177,6 +182,7 @@ add_task(async function test_CtoPtoC_multipart() {
   let browser1 = gBrowser.getBrowserForTab(tab1);
 
   let blob = await ContentTask.spawn(browser1, null, function() {
+    Cu.importGlobalProperties(["Blob"]);
     return new Blob(["!"]);
   });
 
@@ -189,6 +195,7 @@ add_task(async function test_CtoPtoC_multipart() {
   let browser2 = gBrowser.getBrowserForTab(tab2);
 
   let status = await ContentTask.spawn(browser2, newBlob, function(blob) {
+    Cu.importGlobalProperties(["Blob"]);
     return new Promise(resolve => {
       let fr = new content.FileReader();
       fr.readAsText(new Blob(["hello ", blob]));
diff --git a/dom/html/test/browser_fullscreen-api-keys.js b/dom/html/test/browser_fullscreen-api-keys.js
index 0d8d61a063f6..63e4552d6465 100644
--- a/dom/html/test/browser_fullscreen-api-keys.js
+++ b/dom/html/test/browser_fullscreen-api-keys.js
@@ -18,7 +18,7 @@ function frameScript() {
   });
   addMessageListener("Test:DispatchUntrustedKeyEvents", msg => {
     var evt = new content.CustomEvent("Test:DispatchKeyEvents", {
-      detail: { code: msg.data }
+      detail: Cu.cloneInto({ code: msg.data }, content),
     });
     content.dispatchEvent(evt);
   });
diff --git a/dom/tests/browser/browser_localStorage_e10s.js b/dom/tests/browser/browser_localStorage_e10s.js
index 403cd1570d73..a2314a52b330 100644
--- a/dom/tests/browser/browser_localStorage_e10s.js
+++ b/dom/tests/browser/browser_localStorage_e10s.js
@@ -160,7 +160,7 @@ async function mutateTabStorage(knownTab, mutations, sentinelValue) {
     knownTab.tab.linkedBrowser,
     { mutations, sentinelValue },
     function(args) {
-      return content.wrappedJSObject.mutateStorage(args);
+      return content.wrappedJSObject.mutateStorage(Cu.cloneInto(args, content));
     });
 }
 
diff --git a/js/xpconnect/tests/mochitest/test_bug628410.html b/js/xpconnect/tests/mochitest/test_bug628410.html
index 1708ae39352a..b4ef84a2c3b9 100644
--- a/js/xpconnect/tests/mochitest/test_bug628410.html
+++ b/js/xpconnect/tests/mochitest/test_bug628410.html
@@ -19,7 +19,17 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=628410
 <script type="application/javascript">
 
 /** Test for Bug 628410 **/
-window.toSource();
+{
+  // window.toSource() will throw if SpecialPowers is defined on the window and
+  // permissive COWs are not enabled for the global that owns its frame message
+  // manager.
+  let sp = window.SpecialPowers;
+  window.SpecialPowers = null;
+
+  window.toSource();
+  window.SpecialPowers = sp;
+}
+
 window.toString();
 InstallTrigger + "";
 console + "";
diff --git a/security/sandbox/test/browser_bug1393259.js b/security/sandbox/test/browser_bug1393259.js
index ce0d184fd515..4a36c42deb8c 100644
--- a/security/sandbox/test/browser_bug1393259.js
+++ b/security/sandbox/test/browser_bug1393259.js
@@ -21,8 +21,6 @@ const kPageURL =
 const environment = Cc["@mozilla.org/process/environment;1"]
                     .getService(Ci.nsIEnvironment);
 
-const InspectorUtils = SpecialPowers.InspectorUtils;
-
 // Parameters for running the python script that registers/unregisters fonts.
 const kPythonPath = "/usr/bin/python";
 const kFontInstallerPath = "browser/security/sandbox/test/mac_register_font.py";
@@ -128,6 +126,8 @@ add_task(async function() {
 
     // Get a list of fonts being used to display the web content.
     let fontList = await ContentTask.spawn(aBrowser, {}, async function() {
+      Cu.importGlobalProperties(["InspectorUtils"]);
+
       let window = content.window.wrappedJSObject;
       let range = window.document.createRange();
       let contentDiv = window.document.getElementById("content");