diff --git a/dom/base/Navigator.cpp b/dom/base/Navigator.cpp
index f5692e100f6d..784b092ff59e 100644
--- a/dom/base/Navigator.cpp
+++ b/dom/base/Navigator.cpp
@@ -1452,8 +1452,7 @@ Navigator::DoNewResolve(JSContext* aCx, JS::Handle<JSObject*> aObject,
     return true;
   }
 
-  nsScriptNameSpaceManager* nameSpaceManager =
-    nsJSRuntime::GetNameSpaceManager();
+  nsScriptNameSpaceManager* nameSpaceManager = GetNameSpaceManager();
   if (!nameSpaceManager) {
     return Throw<true>(aCx, NS_ERROR_NOT_INITIALIZED);
   }
@@ -1567,8 +1566,7 @@ void
 Navigator::GetOwnPropertyNames(JSContext* aCx, nsTArray<nsString>& aNames,
                                ErrorResult& aRv)
 {
-  nsScriptNameSpaceManager *nameSpaceManager =
-    nsJSRuntime::GetNameSpaceManager();
+  nsScriptNameSpaceManager *nameSpaceManager = GetNameSpaceManager();
   if (!nameSpaceManager) {
     NS_ERROR("Can't get namespace manager.");
     aRv.Throw(NS_ERROR_UNEXPECTED);
diff --git a/dom/base/nsDOMClassInfo.cpp b/dom/base/nsDOMClassInfo.cpp
index afe13845ce60..392df1c053c9 100644
--- a/dom/base/nsDOMClassInfo.cpp
+++ b/dom/base/nsDOMClassInfo.cpp
@@ -911,8 +911,7 @@ CutPrefix(const char *aName) {
 nsresult
 nsDOMClassInfo::RegisterClassProtos(int32_t aClassInfoID)
 {
-  nsScriptNameSpaceManager *nameSpaceManager =
-    nsJSRuntime::GetNameSpaceManager();
+  nsScriptNameSpaceManager *nameSpaceManager = GetNameSpaceManager();
   NS_ENSURE_TRUE(nameSpaceManager, NS_ERROR_NOT_INITIALIZED);
   bool found_old;
 
@@ -964,8 +963,7 @@ nsDOMClassInfo::RegisterClassProtos(int32_t aClassInfoID)
 nsresult
 nsDOMClassInfo::RegisterExternalClasses()
 {
-  nsScriptNameSpaceManager *nameSpaceManager =
-    nsJSRuntime::GetNameSpaceManager();
+  nsScriptNameSpaceManager *nameSpaceManager = GetNameSpaceManager();
   NS_ENSURE_TRUE(nameSpaceManager, NS_ERROR_NOT_INITIALIZED);
 
   nsCOMPtr<nsIComponentRegistrar> registrar;
@@ -1097,7 +1095,7 @@ nsDOMClassInfo::Init()
 
   NS_ENSURE_TRUE(!sIsInitialized, NS_ERROR_ALREADY_INITIALIZED);
 
-  nsScriptNameSpaceManager *nameSpaceManager = nsJSRuntime::GetNameSpaceManager();
+  nsScriptNameSpaceManager *nameSpaceManager = GetNameSpaceManager();
   NS_ENSURE_TRUE(nameSpaceManager, NS_ERROR_NOT_INITIALIZED);
 
   nsresult rv = CallGetService(nsIXPConnect::GetCID(), &sXPConnect);
@@ -2072,8 +2070,7 @@ nsDOMClassInfo::PostCreatePrototype(JSContext * cx, JSObject * aProto)
     return NS_ERROR_FAILURE;
   }
 
-  nsScriptNameSpaceManager *nameSpaceManager =
-    nsJSRuntime::GetNameSpaceManager();
+  nsScriptNameSpaceManager *nameSpaceManager = GetNameSpaceManager();
   NS_ENSURE_TRUE(nameSpaceManager, NS_OK);
 
   bool unused;
@@ -2271,8 +2268,7 @@ nsWindowSH::Enumerate(nsIXPConnectWrappedNative *wrapper, JSContext *cx,
     }
 
     // Now resolve everything from the namespace manager
-    nsScriptNameSpaceManager *nameSpaceManager =
-      nsJSRuntime::GetNameSpaceManager();
+    nsScriptNameSpaceManager *nameSpaceManager = GetNameSpaceManager();
     if (!nameSpaceManager) {
       NS_ERROR("Can't get namespace manager.");
       return NS_ERROR_UNEXPECTED;
@@ -2556,8 +2552,7 @@ private:
   {
     *aNameStruct = nullptr;
 
-    nsScriptNameSpaceManager *nameSpaceManager =
-      nsJSRuntime::GetNameSpaceManager();
+    nsScriptNameSpaceManager *nameSpaceManager = GetNameSpaceManager();
     if (!nameSpaceManager) {
       NS_ERROR("Can't get namespace manager.");
       return NS_ERROR_UNEXPECTED;
@@ -2764,8 +2759,7 @@ nsDOMConstructor::HasInstance(nsIXPConnectWrappedNative *wrapper,
     return NS_OK;
   }
 
-  nsScriptNameSpaceManager *nameSpaceManager =
-    nsJSRuntime::GetNameSpaceManager();
+  nsScriptNameSpaceManager *nameSpaceManager = GetNameSpaceManager();
   NS_ASSERTION(nameSpaceManager, "Can't get namespace manager?");
 
   const nsIID *class_iid;
@@ -3158,8 +3152,7 @@ nsWindowSH::GlobalResolve(nsGlobalWindow *aWin, JSContext *cx,
 {
   *did_resolve = false;
 
-  nsScriptNameSpaceManager *nameSpaceManager =
-    nsJSRuntime::GetNameSpaceManager();
+  nsScriptNameSpaceManager *nameSpaceManager = GetNameSpaceManager();
   NS_ENSURE_TRUE(nameSpaceManager, NS_ERROR_NOT_INITIALIZED);
 
   nsDependentJSString name(id);
diff --git a/dom/base/nsDOMScriptObjectFactory.cpp b/dom/base/nsDOMScriptObjectFactory.cpp
index 2ff783c925b5..c73f476f2bf4 100644
--- a/dom/base/nsDOMScriptObjectFactory.cpp
+++ b/dom/base/nsDOMScriptObjectFactory.cpp
@@ -31,6 +31,8 @@
 #endif
 #include "nsThreadUtils.h"
 
+using mozilla::dom::GetNameSpaceManager;
+
 nsIExceptionProvider* gExceptionProvider = nullptr;
 
 nsDOMScriptObjectFactory::nsDOMScriptObjectFactory()
@@ -76,7 +78,7 @@ nsDOMScriptObjectFactory::GetClassInfoInstance(nsDOMClassInfoID aID)
 NS_IMETHODIMP_(nsISupports *)
 nsDOMScriptObjectFactory::GetExternalClassInfoInstance(const nsAString& aName)
 {
-  nsScriptNameSpaceManager *nameSpaceManager = nsJSRuntime::GetNameSpaceManager();
+  nsScriptNameSpaceManager *nameSpaceManager = GetNameSpaceManager();
   NS_ENSURE_TRUE(nameSpaceManager, nullptr);
 
   const nsGlobalNameStruct *globalStruct = nameSpaceManager->LookupName(aName);
@@ -153,7 +155,7 @@ nsDOMScriptObjectFactory::RegisterDOMClassInfo(const char *aName,
 					       bool aHasClassInterface,
 					       const nsCID *aConstructorCID)
 {
-  nsScriptNameSpaceManager *nameSpaceManager = nsJSRuntime::GetNameSpaceManager();
+  nsScriptNameSpaceManager *nameSpaceManager = GetNameSpaceManager();
   NS_ENSURE_TRUE(nameSpaceManager, NS_ERROR_NOT_INITIALIZED);
 
   return nameSpaceManager->RegisterDOMCIData(aName,
diff --git a/dom/base/nsJSEnvironment.cpp b/dom/base/nsJSEnvironment.cpp
index 04ecfb609f84..9691d128e22c 100644
--- a/dom/base/nsJSEnvironment.cpp
+++ b/dom/base/nsJSEnvironment.cpp
@@ -135,7 +135,7 @@ static PRLogModuleInfo* gJSDiagnostics;
 
 #define NS_MAJOR_FORGET_SKIPPABLE_CALLS 2
 
-// if you add statics here, add them to the list in nsJSRuntime::Startup
+// if you add statics here, add them to the list in StartupJSEnvironment
 
 static nsITimer *sGCTimer;
 static nsITimer *sShrinkGCBuffersTimer;
@@ -1153,7 +1153,7 @@ nsJSContext::InitContext()
 nsresult
 nsJSContext::InitializeExternalClasses()
 {
-  nsScriptNameSpaceManager *nameSpaceManager = nsJSRuntime::GetNameSpaceManager();
+  nsScriptNameSpaceManager *nameSpaceManager = GetNameSpaceManager();
   NS_ENSURE_TRUE(nameSpaceManager, NS_ERROR_NOT_INITIALIZED);
 
   return nameSpaceManager->InitForContext(this);
@@ -2565,7 +2565,7 @@ nsJSContext::LikelyShortLivingObjectCreated()
 }
 
 void
-nsJSRuntime::Startup()
+mozilla::dom::StartupJSEnvironment()
 {
   // initialize all our statics, so that we can restart XPCOM
   sGCTimer = sFullGCTimer = sCCTimer = nullptr;
@@ -2866,7 +2866,7 @@ nsJSContext::EnsureStatics()
 }
 
 nsScriptNameSpaceManager*
-nsJSRuntime::GetNameSpaceManager()
+mozilla::dom::GetNameSpaceManager()
 {
   if (sDidShutdown)
     return nullptr;
@@ -2883,7 +2883,7 @@ nsJSRuntime::GetNameSpaceManager()
 }
 
 void
-nsJSRuntime::Shutdown()
+mozilla::dom::ShutdownJSEnvironment()
 {
   KillTimers();
 
diff --git a/dom/base/nsJSEnvironment.h b/dom/base/nsJSEnvironment.h
index b2a046aabf81..c54e0e07e228 100644
--- a/dom/base/nsJSEnvironment.h
+++ b/dom/base/nsJSEnvironment.h
@@ -184,14 +184,17 @@ private:
 
 class nsIJSRuntimeService;
 
-namespace nsJSRuntime
-{
-  void Startup();
-  void Shutdown();
-  // Get the NameSpaceManager, creating if necessary
-  nsScriptNameSpaceManager* GetNameSpaceManager();
+namespace mozilla {
+namespace dom {
 
-};
+void StartupJSEnvironment();
+void ShutdownJSEnvironment();
+
+// Get the NameSpaceManager, creating if necessary
+nsScriptNameSpaceManager* GetNameSpaceManager();
+
+} // namespace dom
+} // namespace mozilla
 
 // An interface for fast and native conversion to/from nsIArray. If an object
 // supports this interface, JS can reach directly in for the argv, and avoid
diff --git a/layout/build/nsLayoutStatics.cpp b/layout/build/nsLayoutStatics.cpp
index 6be376b3ddf9..2df135b62ab7 100644
--- a/layout/build/nsLayoutStatics.cpp
+++ b/layout/build/nsLayoutStatics.cpp
@@ -149,7 +149,7 @@ nsLayoutStatics::Initialize()
   nsColorNames::AddRefTable();
   nsGkAtoms::AddRefAtoms();
 
-  nsJSRuntime::Startup();
+  StartupJSEnvironment();
   rv = nsRegion::InitStatic();
   if (NS_FAILED(rv)) {
     NS_ERROR("Could not initialize nsRegion");
@@ -334,7 +334,7 @@ nsLayoutStatics::Shutdown()
   nsLayoutStylesheetCache::Shutdown();
   NS_NameSpaceManagerShutdown();
 
-  nsJSRuntime::Shutdown();
+  ShutdownJSEnvironment();
   nsGlobalWindow::ShutDown();
   nsDOMClassInfo::ShutDown();
   nsListControlFrame::Shutdown();