--- a/dom/base/Navigator.cpp
+++ b/dom/base/Navigator.cpp
@@ -70,18 +70,16 @@
 #include "nsIScriptError.h"
 
 #include "mozilla/dom/MediaDevices.h"
 #include "MediaManager.h"
 
 #include "nsIDOMGlobalPropertyInitializer.h"
 #include "nsJSUtils.h"
 
-#include "nsScriptNameSpaceManager.h"
-
 #include "mozilla/dom/NavigatorBinding.h"
 #include "mozilla/dom/Promise.h"
 
 #include "nsIUploadChannel2.h"
 #include "mozilla/dom/FormData.h"
 #include "nsIDocShell.h"
 
 #include "mozilla/dom/WorkerPrivate.h"

--- a/dom/base/moz.build
+++ b/dom/base/moz.build
@@ -88,17 +88,16 @@ EXPORTS += [
     'nsIDOMClassInfo.h',
     'nsIGlobalObject.h',
     'nsImageLoadingContent.h',
     'nsIMutationObserver.h',
     'nsINode.h',
     'nsINodeList.h',
     'nsIScriptContext.h',
     'nsIScriptGlobalObject.h',
-    'nsIScriptNameSpaceManager.h',
     'nsIScriptObjectPrincipal.h',
     'nsIScriptTimeoutHandler.h',
     'nsIStyleSheetLinkingElement.h',
     'nsITimeoutHandler.h',
     'nsJSEnvironment.h',
     'nsJSUtils.h',
     'nsLineBreaker.h',
     'nsMappedAttributeElement.h',
@@ -327,17 +326,16 @@ UNIFIED_SOURCES += [
     'nsNodeUtils.cpp',
     'nsOpenURIInFrameParams.cpp',
     'nsPerformanceMetrics.cpp',
     'nsPlainTextSerializer.cpp',
     'nsPropertyTable.cpp',
     'nsQueryContentEventResult.cpp',
     'nsRange.cpp',
     'nsScreen.cpp',
-    'nsScriptNameSpaceManager.cpp',
     'nsStructuredCloneContainer.cpp',
     'nsStubAnimationObserver.cpp',
     'nsStubDocumentObserver.cpp',
     'nsStubMutationObserver.cpp',
     'nsStyledElement.cpp',
     'nsStyleLinkElement.cpp',
     'nsSyncLoadService.cpp',
     'nsTextFragment.cpp',

--- a/dom/base/nsDOMClassInfo.cpp
+++ b/dom/base/nsDOMClassInfo.cpp
@@ -42,19 +42,16 @@
 #include "nsIDOMDocument.h"
 #include "nsIDOMEvent.h"
 #include "nsIDOMEventListener.h"
 #include "nsContentUtils.h"
 #include "nsIDOMGlobalPropertyInitializer.h"
 #include "mozilla/Attributes.h"
 #include "mozilla/Telemetry.h"
 
-// Window scriptable helper includes
-#include "nsScriptNameSpaceManager.h"
-
 // DOM base includes
 #include "nsIDOMWindow.h"
 #include "nsPIDOMWindow.h"
 
 // DOM core includes
 #include "nsError.h"
 
 // Event related includes
@@ -165,75 +162,17 @@ nsWindowSH::GlobalResolve(nsGlobalWindow
     if (NS_WARN_IF(!shim)) {
       return NS_ERROR_OUT_OF_MEMORY;
     }
     FillPropertyDescriptor(desc, obj, JS::ObjectValue(*shim), /* readOnly = */ false);
     return NS_OK;
   }
 #endif
 
-  nsScriptNameSpaceManager *nameSpaceManager = GetNameSpaceManager();
-  NS_ENSURE_TRUE(nameSpaceManager, NS_ERROR_NOT_INITIALIZED);
-
-  // Note - Our only caller is nsGlobalWindow::DoResolve, which checks that
-  // JSID_IS_STRING(id) is true.
-  nsAutoJSString name;
-  if (!name.init(cx, JSID_TO_STRING(id))) {
-    return NS_ERROR_OUT_OF_MEMORY;
-  }
-
-  const char16_t *class_name = nullptr;
-  const nsGlobalNameStruct *name_struct =
-    nameSpaceManager->LookupName(name, &class_name);
-
-  if (!name_struct) {
-    return NS_OK;
-  }
-
-  // The class_name had better match our name
-  MOZ_ASSERT(name.Equals(class_name));
-
-  NS_ENSURE_TRUE(class_name, NS_ERROR_UNEXPECTED);
-
-  nsresult rv = NS_OK;
-
-  if (name_struct->mType == nsGlobalNameStruct::eTypeProperty) {
-    // Before defining a global property, check for a named subframe of the
-    // same name. If it exists, we don't want to shadow it.
-    if (nsCOMPtr<nsPIDOMWindowOuter> childWin = aWin->GetChildWindow(name)) {
-      return NS_OK;
-    }
-
-    nsCOMPtr<nsISupports> native(do_CreateInstance(name_struct->mCID, &rv));
-    NS_ENSURE_SUCCESS(rv, rv);
-
-    JS::Rooted<JS::Value> prop_val(cx, JS::UndefinedValue()); // Property value.
-
-    nsCOMPtr<nsIDOMGlobalPropertyInitializer> gpi(do_QueryInterface(native));
-    if (gpi) {
-      rv = gpi->Init(aWin->AsInner(), &prop_val);
-      NS_ENSURE_SUCCESS(rv, rv);
-    }
-
-    if (prop_val.isPrimitive() && !prop_val.isNull()) {
-      rv = nsContentUtils::WrapNative(cx, native, &prop_val, true);
-    }
-
-    NS_ENSURE_SUCCESS(rv, rv);
-
-    if (!JS_WrapValue(cx, &prop_val)) {
-      return NS_ERROR_UNEXPECTED;
-    }
-
-    FillPropertyDescriptor(desc, obj, prop_val, false);
-
-    return NS_OK;
-  }
-
-  return rv;
+  return NS_OK;
 }
 
 struct InterfaceShimEntry {
   const char *geckoName;
   const char *domName;
 };
 
 // We add shims from Components.interfaces.nsIDOMFoo to window.Foo for each

--- a/dom/base/nsGlobalWindowInner.cpp
+++ b/dom/base/nsGlobalWindowInner.cpp
@@ -46,17 +46,16 @@
 #include "nsIDocShellTreeOwner.h"
 #include "nsIDocumentLoader.h"
 #include "nsIInterfaceRequestorUtils.h"
 #include "nsIPermissionManager.h"
 #include "nsIScriptContext.h"
 #include "nsIScriptTimeoutHandler.h"
 #include "nsITimeoutHandler.h"
 #include "nsIController.h"
-#include "nsScriptNameSpaceManager.h"
 #include "nsISlowScriptDebug.h"
 #include "nsWindowMemoryReporter.h"
 #include "nsWindowSizes.h"
 #include "WindowNamedPropertiesHandler.h"
 #include "nsFrameSelection.h"
 #include "nsNetUtil.h"
 #include "nsVariant.h"
 #include "nsPrintfCString.h"
@@ -2934,30 +2933,17 @@ nsGlobalWindowInner::MayResolve(jsid aId
 
   if (aId == XPCJSRuntime::Get()->GetStringID(XPCJSContext::IDX_CONTROLLERS) ||
       aId == XPCJSRuntime::Get()->GetStringID(XPCJSContext::IDX_CONTROLLERS_CLASS)) {
     // We only resolve .controllers/.Controllers in release builds and on non-chrome
     // windows, but let's not worry about any of that stuff.
     return true;
   }
 
-  if (WebIDLGlobalNameHash::MayResolve(aId)) {
-    return true;
-  }
-
-  nsScriptNameSpaceManager *nameSpaceManager = PeekNameSpaceManager();
-  if (!nameSpaceManager) {
-    // Really shouldn't happen.  Fail safe.
-    return true;
-  }
-
-  nsAutoString name;
-  AssignJSFlatString(name, JSID_TO_FLAT_STRING(aId));
-
-  return nameSpaceManager->LookupName(name);
+  return WebIDLGlobalNameHash::MayResolve(aId);
 }
 
 void
 nsGlobalWindowInner::GetOwnPropertyNames(JSContext* aCx, JS::AutoIdVector& aNames,
                                          bool aEnumerableOnly, ErrorResult& aRv)
 {
   if (aEnumerableOnly) {
     // The names we would return from here get defined on the window via one of
@@ -2969,50 +2955,34 @@ nsGlobalWindowInner::GetOwnPropertyNames
     //
     // So in the aEnumerableOnly case we have nothing to do.
     return;
   }
 
   // "Components" is marked as enumerable but only resolved on demand :-/.
   //aNames.AppendElement(NS_LITERAL_STRING("Components"));
 
-  nsScriptNameSpaceManager* nameSpaceManager = GetNameSpaceManager();
-  if (nameSpaceManager) {
-    JS::Rooted<JSObject*> wrapper(aCx, GetWrapper());
-
-    // There are actually two ways we can get called here: For normal
-    // enumeration or for Xray enumeration.  In the latter case, we want to
-    // return all possible WebIDL names, because we don't really support
-    // deleting these names off our Xray; trying to resolve them will just make
-    // them come back.  In the former case, we want to avoid returning deleted
-    // names.  But the JS engine already knows about the non-deleted
-    // already-resolved names, so we can just return the so-far-unresolved ones.
-    //
-    // We can tell which case we're in by whether aCx is in our wrapper's
-    // compartment.  If not, we're in the Xray case.
-    WebIDLGlobalNameHash::NameType nameType =
-      js::IsObjectInContextCompartment(wrapper, aCx) ?
-        WebIDLGlobalNameHash::UnresolvedNamesOnly :
-        WebIDLGlobalNameHash::AllNames;
-    if (!WebIDLGlobalNameHash::GetNames(aCx, wrapper, nameType, aNames)) {
-      aRv.NoteJSContextException(aCx);
-    }
-
-    for (auto i = nameSpaceManager->GlobalNameIter(); !i.Done(); i.Next()) {
-      const GlobalNameMapEntry* entry = i.Get();
-      // Just append all of these; even if they get deleted our resolve hook
-      // just goes ahead and recreates them.
-      JSString* str = JS_AtomizeUCStringN(aCx,
-                                          entry->mKey.BeginReading(),
-                                          entry->mKey.Length());
-      if (!str || !aNames.append(NON_INTEGER_ATOM_TO_JSID(str))) {
-        aRv.NoteJSContextException(aCx);
-        return;
-      }
-    }
+  JS::Rooted<JSObject*> wrapper(aCx, GetWrapper());
+
+  // There are actually two ways we can get called here: For normal
+  // enumeration or for Xray enumeration.  In the latter case, we want to
+  // return all possible WebIDL names, because we don't really support
+  // deleting these names off our Xray; trying to resolve them will just make
+  // them come back.  In the former case, we want to avoid returning deleted
+  // names.  But the JS engine already knows about the non-deleted
+  // already-resolved names, so we can just return the so-far-unresolved ones.
+  //
+  // We can tell which case we're in by whether aCx is in our wrapper's
+  // compartment.  If not, we're in the Xray case.
+  WebIDLGlobalNameHash::NameType nameType =
+    js::IsObjectInContextCompartment(wrapper, aCx) ?
+      WebIDLGlobalNameHash::UnresolvedNamesOnly :
+      WebIDLGlobalNameHash::AllNames;
+  if (!WebIDLGlobalNameHash::GetNames(aCx, wrapper, nameType, aNames)) {
+    aRv.NoteJSContextException(aCx);
   }
 }
 
 /* static */ bool
 nsGlobalWindowInner::IsPrivilegedChromeWindow(JSContext* aCx, JSObject* aObj)
 {
   // For now, have to deal with XPConnect objects here.
   return xpc::WindowOrNull(aObj)->IsChromeWindow() &&

--- a/dom/base/nsGlobalWindowOuter.cpp
+++ b/dom/base/nsGlobalWindowOuter.cpp
@@ -44,17 +44,16 @@
 #include "mozilla/dom/power/PowerManagerService.h"
 #include "nsIDocShellTreeOwner.h"
 #include "nsIInterfaceRequestorUtils.h"
 #include "nsIPermissionManager.h"
 #include "nsIScriptContext.h"
 #include "nsIScriptTimeoutHandler.h"
 #include "nsITimeoutHandler.h"
 #include "nsIController.h"
-#include "nsScriptNameSpaceManager.h"
 #include "nsISlowScriptDebug.h"
 #include "nsWindowMemoryReporter.h"
 #include "nsWindowSizes.h"
 #include "WindowNamedPropertiesHandler.h"
 #include "nsFrameSelection.h"
 #include "nsNetUtil.h"
 #include "nsVariant.h"
 #include "nsPrintfCString.h"

deleted file mode 100644
--- a/dom/base/nsIScriptNameSpaceManager.h
+++ /dev/null
@@ -1,10 +0,0 @@
-/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
-/* vim: set ts=8 sts=2 et sw=2 tw=80: */
-/* 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/. */
-
-#ifndef nsIScriptNameSpaceManager_h__
-#define nsIScriptNameSpaceManager_h__
-
-#endif /* nsIScriptNameSpaceManager_h__ */

--- a/dom/base/nsJSEnvironment.cpp
+++ b/dom/base/nsJSEnvironment.cpp
@@ -48,17 +48,16 @@
 #include "jsapi.h"
 #include "js/Wrapper.h"
 #include "js/SliceBudget.h"
 #include "nsIArray.h"
 #include "nsIObjectInputStream.h"
 #include "nsIObjectOutputStream.h"
 #include "WrapperFactory.h"
 #include "nsGlobalWindow.h"
-#include "nsScriptNameSpaceManager.h"
 #include "mozilla/AutoRestore.h"
 #include "mozilla/MainThreadIdlePeriod.h"
 #include "mozilla/StaticPtr.h"
 #include "mozilla/dom/DOMException.h"
 #include "mozilla/dom/DOMExceptionBinding.h"
 #include "mozilla/dom/Element.h"
 #include "mozilla/dom/ErrorEvent.h"
 #include "mozilla/dom/FetchUtil.h"
@@ -194,17 +193,16 @@ static uint32_t sRemovedPurples = 0;
 static uint32_t sForgetSkippableBeforeCC = 0;
 static uint32_t sPreviousSuspectedCount = 0;
 static uint32_t sCleanupsSinceLastGC = UINT32_MAX;
 static bool sNeedsFullCC = false;
 static bool sNeedsFullGC = false;
 static bool sNeedsGCAfterCC = false;
 static bool sIncrementalCC = false;
 static int32_t sActiveIntersliceGCBudget = 5; // ms;
-static nsScriptNameSpaceManager *gNameSpaceManager;
 
 static PRTime sFirstCollectionTime;
 
 static bool sIsInitialized;
 static bool sDidShutdown;
 static bool sShuttingDown;
 
 // nsJSEnvironmentObserver observes the memory-pressure notifications
@@ -2462,17 +2460,16 @@ mozilla::dom::StartupJSEnvironment()
   sLoadingInProgress = false;
   sCCollectedWaitingForGC = 0;
   sCCollectedZonesWaitingForGC = 0;
   sLikelyShortLivingObjectsNeedingGC = 0;
   sPostGCEventsToConsole = false;
   sNeedsFullCC = false;
   sNeedsFullGC = true;
   sNeedsGCAfterCC = false;
-  gNameSpaceManager = nullptr;
   sIsInitialized = false;
   sDidShutdown = false;
   sShuttingDown = false;
   gCCStats.Init();
 }
 
 static void
 SetGCParameter(JSGCParamKey aParam, uint32_t aValue)
@@ -2800,46 +2797,21 @@ nsJSContext::EnsureStatics()
   obs->AddObserver(observer, "user-interaction-inactive", false);
   obs->AddObserver(observer, "user-interaction-active", false);
   obs->AddObserver(observer, "quit-application", false);
   obs->AddObserver(observer, NS_XPCOM_SHUTDOWN_OBSERVER_ID, false);
 
   sIsInitialized = true;
 }
 
-nsScriptNameSpaceManager*
-mozilla::dom::GetNameSpaceManager()
-{
-  if (sDidShutdown)
-    return nullptr;
-
-  if (!gNameSpaceManager) {
-    gNameSpaceManager = new nsScriptNameSpaceManager;
-    NS_ADDREF(gNameSpaceManager);
-
-    nsresult rv = gNameSpaceManager->Init();
-    NS_ENSURE_SUCCESS(rv, nullptr);
-  }
-
-  return gNameSpaceManager;
-}
-
-nsScriptNameSpaceManager*
-mozilla::dom::PeekNameSpaceManager()
-{
-  return gNameSpaceManager;
-}
-
 void
 mozilla::dom::ShutdownJSEnvironment()
 {
   KillTimers();
 
-  NS_IF_RELEASE(gNameSpaceManager);
-
   sShuttingDown = true;
   sDidShutdown = true;
 }
 
 // A fast-array class for JS.  This class supports both nsIJSScriptArray and
 // nsIArray.  If it is JS itself providing and consuming this class, all work
 // can be done via nsIJSScriptArray, and avoid the conversion of elements
 // to/from nsISupports.

--- a/dom/base/nsJSEnvironment.h
+++ b/dom/base/nsJSEnvironment.h
@@ -15,17 +15,16 @@
 #include "nsIXPConnect.h"
 #include "nsIArray.h"
 #include "mozilla/Attributes.h"
 #include "mozilla/TimeStamp.h"
 #include "nsThreadUtils.h"
 #include "xpcpublic.h"
 
 class nsICycleCollectorListener;
-class nsScriptNameSpaceManager;
 class nsIDocShell;
 
 namespace mozilla {
 template <class> class Maybe;
 struct CycleCollectorResults;
 } // namespace mozilla
 
 // The amount of time we wait between a request to GC (due to leaving
@@ -163,22 +162,16 @@ private:
 };
 
 namespace mozilla {
 namespace dom {
 
 void StartupJSEnvironment();
 void ShutdownJSEnvironment();
 
-// Get the NameSpaceManager, creating if necessary
-nsScriptNameSpaceManager* GetNameSpaceManager();
-
-// Peek the NameSpaceManager, without creating it.
-nsScriptNameSpaceManager* PeekNameSpaceManager();
-
 // Runnable that's used to do async error reporting
 class AsyncErrorReporter final : public mozilla::Runnable
 {
 public:
   // aWindow may be null if this error report is not associated with a window
   explicit AsyncErrorReporter(xpc::ErrorReport* aReport)
     : Runnable("dom::AsyncErrorReporter")
     , mReport(aReport)

deleted file mode 100644
--- a/dom/base/nsScriptNameSpaceManager.cpp
+++ /dev/null
@@ -1,290 +0,0 @@
-/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
-/* vim: set ts=8 sts=2 et sw=2 tw=80: */
-/* 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/. */
-
-#include "nsScriptNameSpaceManager.h"
-#include "nsCOMPtr.h"
-#include "nsIComponentManager.h"
-#include "nsIComponentRegistrar.h"
-#include "nsICategoryManager.h"
-#include "nsIServiceManager.h"
-#include "nsXPCOM.h"
-#include "nsISupportsPrimitives.h"
-#include "nsIScriptNameSpaceManager.h"
-#include "nsIScriptContext.h"
-#include "nsIInterfaceInfoManager.h"
-#include "nsIInterfaceInfo.h"
-#include "xptinfo.h"
-#include "nsString.h"
-#include "nsReadableUtils.h"
-#include "nsHashKeys.h"
-#include "nsDOMClassInfo.h"
-#include "nsCRT.h"
-#include "nsIObserverService.h"
-#include "nsISimpleEnumerator.h"
-#include "mozilla/dom/BindingUtils.h"
-#include "mozilla/dom/WebIDLGlobalNameHash.h"
-#include "mozilla/MemoryReporting.h"
-#include "mozilla/Preferences.h"
-#include "mozilla/Services.h"
-
-#define NS_INTERFACE_PREFIX "nsI"
-#define NS_DOM_INTERFACE_PREFIX "nsIDOM"
-
-using namespace mozilla;
-using namespace mozilla::dom;
-
-static PLDHashNumber
-GlobalNameHashHashKey(const void *key)
-{
-  const nsAString *str = static_cast<const nsAString *>(key);
-  return HashString(*str);
-}
-
-static bool
-GlobalNameHashMatchEntry(const PLDHashEntryHdr *entry, const void *key)
-{
-  const GlobalNameMapEntry *e =
-    static_cast<const GlobalNameMapEntry *>(entry);
-  const nsAString *str = static_cast<const nsAString *>(key);
-
-  return str->Equals(e->mKey);
-}
-
-static void
-GlobalNameHashClearEntry(PLDHashTable *table, PLDHashEntryHdr *entry)
-{
-  GlobalNameMapEntry *e = static_cast<GlobalNameMapEntry *>(entry);
-
-  // An entry is being cleared, let the key (nsString) do its own
-  // cleanup.
-  e->mKey.~nsString();
-
-  // This will set e->mGlobalName.mType to
-  // nsGlobalNameStruct::eTypeNotInitialized
-  memset(&e->mGlobalName, 0, sizeof(nsGlobalNameStruct));
-}
-
-static void
-GlobalNameHashInitEntry(PLDHashEntryHdr *entry, const void *key)
-{
-  GlobalNameMapEntry *e = static_cast<GlobalNameMapEntry *>(entry);
-  const nsAString *keyStr = static_cast<const nsAString *>(key);
-
-  // Initialize the key in the entry with placement new
-  new (&e->mKey) nsString(*keyStr);
-
-  // This will set e->mGlobalName.mType to
-  // nsGlobalNameStruct::eTypeNotInitialized
-  memset(&e->mGlobalName, 0, sizeof(nsGlobalNameStruct));
-}
-
-NS_IMPL_ISUPPORTS(
-  nsScriptNameSpaceManager,
-  nsIObserver,
-  nsISupportsWeakReference,
-  nsIMemoryReporter)
-
-static const PLDHashTableOps hash_table_ops =
-{
-  GlobalNameHashHashKey,
-  GlobalNameHashMatchEntry,
-  PLDHashTable::MoveEntryStub,
-  GlobalNameHashClearEntry,
-  GlobalNameHashInitEntry
-};
-
-#define GLOBALNAME_HASHTABLE_INITIAL_LENGTH          32
-
-nsScriptNameSpaceManager::nsScriptNameSpaceManager()
-  : mGlobalNames(&hash_table_ops, sizeof(GlobalNameMapEntry),
-                 GLOBALNAME_HASHTABLE_INITIAL_LENGTH)
-{
-}
-
-nsScriptNameSpaceManager::~nsScriptNameSpaceManager()
-{
-  UnregisterWeakMemoryReporter(this);
-}
-
-nsGlobalNameStruct *
-nsScriptNameSpaceManager::AddToHash(const char *aKey,
-                                    const char16_t **aClassName)
-{
-  NS_ConvertASCIItoUTF16 key(aKey);
-  auto entry = static_cast<GlobalNameMapEntry*>(mGlobalNames.Add(&key, fallible));
-  if (!entry) {
-    return nullptr;
-  }
-
-  WebIDLGlobalNameHash::Remove(aKey, key.Length());
-
-  if (aClassName) {
-    *aClassName = entry->mKey.get();
-  }
-
-  return &entry->mGlobalName;
-}
-
-void
-nsScriptNameSpaceManager::RemoveFromHash(const nsAString *aKey)
-{
-  mGlobalNames.Remove(aKey);
-}
-
-nsresult
-nsScriptNameSpaceManager::FillHash(nsICategoryManager *aCategoryManager,
-                                   const char *aCategory)
-{
-  nsCOMPtr<nsISimpleEnumerator> e;
-  nsresult rv = aCategoryManager->EnumerateCategory(aCategory,
-                                                    getter_AddRefs(e));
-  NS_ENSURE_SUCCESS(rv, rv);
-
-  nsCOMPtr<nsISupports> entry;
-  while (NS_SUCCEEDED(e->GetNext(getter_AddRefs(entry)))) {
-    rv = AddCategoryEntryToHash(aCategoryManager, aCategory, entry);
-    if (NS_FAILED(rv)) {
-      return rv;
-    }
-  }
-
-  return NS_OK;
-}
-
-
-nsresult
-nsScriptNameSpaceManager::Init()
-{
-  RegisterWeakMemoryReporter(this);
-
-  nsresult rv = NS_OK;
-
-  nsCOMPtr<nsICategoryManager> cm =
-    do_GetService(NS_CATEGORYMANAGER_CONTRACTID, &rv);
-  NS_ENSURE_SUCCESS(rv, rv);
-
-  // Initial filling of the has table has been done.
-  // Now, listen for changes.
-  nsCOMPtr<nsIObserverService> serv =
-    mozilla::services::GetObserverService();
-
-  if (serv) {
-    serv->AddObserver(this, NS_XPCOM_CATEGORY_ENTRY_ADDED_OBSERVER_ID, true);
-    serv->AddObserver(this, NS_XPCOM_CATEGORY_ENTRY_REMOVED_OBSERVER_ID, true);
-  }
-
-  return NS_OK;
-}
-
-const nsGlobalNameStruct*
-nsScriptNameSpaceManager::LookupName(const nsAString& aName,
-                                     const char16_t **aClassName)
-{
-  auto entry = static_cast<GlobalNameMapEntry*>(mGlobalNames.Search(&aName));
-
-  if (entry) {
-    if (aClassName) {
-      *aClassName = entry->mKey.get();
-    }
-    return &entry->mGlobalName;
-  }
-
-  if (aClassName) {
-    *aClassName = nullptr;
-  }
-  return nullptr;
-}
-
-nsresult
-nsScriptNameSpaceManager::OperateCategoryEntryHash(nsICategoryManager* aCategoryManager,
-                                                   const char* aCategory,
-                                                   nsISupports* aEntry,
-                                                   bool aRemove)
-{
-  MOZ_ASSERT(aCategoryManager);
-  return NS_OK;
-}
-
-nsresult
-nsScriptNameSpaceManager::AddCategoryEntryToHash(nsICategoryManager* aCategoryManager,
-                                                 const char* aCategory,
-                                                 nsISupports* aEntry)
-{
-  return OperateCategoryEntryHash(aCategoryManager, aCategory, aEntry,
-                                  /* aRemove = */ false);
-}
-
-nsresult
-nsScriptNameSpaceManager::RemoveCategoryEntryFromHash(nsICategoryManager* aCategoryManager,
-                                                      const char* aCategory,
-                                                      nsISupports* aEntry)
-{
-  return OperateCategoryEntryHash(aCategoryManager, aCategory, aEntry,
-                                  /* aRemove = */ true);
-}
-
-NS_IMETHODIMP
-nsScriptNameSpaceManager::Observe(nsISupports* aSubject, const char* aTopic,
-                                  const char16_t* aData)
-{
-  if (!aData) {
-    return NS_OK;
-  }
-
-  if (!strcmp(aTopic, NS_XPCOM_CATEGORY_ENTRY_ADDED_OBSERVER_ID)) {
-    nsCOMPtr<nsICategoryManager> cm =
-      do_GetService(NS_CATEGORYMANAGER_CONTRACTID);
-    if (!cm) {
-      return NS_OK;
-    }
-
-    return AddCategoryEntryToHash(cm, NS_ConvertUTF16toUTF8(aData).get(),
-                                  aSubject);
-  } else if (!strcmp(aTopic, NS_XPCOM_CATEGORY_ENTRY_REMOVED_OBSERVER_ID)) {
-    nsCOMPtr<nsICategoryManager> cm =
-      do_GetService(NS_CATEGORYMANAGER_CONTRACTID);
-    if (!cm) {
-      return NS_OK;
-    }
-
-    return RemoveCategoryEntryFromHash(cm, NS_ConvertUTF16toUTF8(aData).get(),
-                                       aSubject);
-  }
-
-  // TODO: we could observe NS_XPCOM_CATEGORY_CLEARED_OBSERVER_ID
-  // but we are safe without it. See bug 600460.
-
-  return NS_OK;
-}
-
-MOZ_DEFINE_MALLOC_SIZE_OF(ScriptNameSpaceManagerMallocSizeOf)
-
-NS_IMETHODIMP
-nsScriptNameSpaceManager::CollectReports(
-  nsIHandleReportCallback* aHandleReport, nsISupports* aData, bool aAnonymize)
-{
-  MOZ_COLLECT_REPORT(
-    "explicit/script-namespace-manager", KIND_HEAP, UNITS_BYTES,
-    SizeOfIncludingThis(ScriptNameSpaceManagerMallocSizeOf),
-    "Memory used for the script namespace manager.");
-
-  return NS_OK;
-}
-
-size_t
-nsScriptNameSpaceManager::SizeOfIncludingThis(
-    mozilla::MallocSizeOf aMallocSizeOf) const
-{
-  size_t n = 0;
-
-  n += mGlobalNames.ShallowSizeOfExcludingThis(aMallocSizeOf);
-  for (auto iter = mGlobalNames.ConstIter(); !iter.Done(); iter.Next()) {
-    auto entry = static_cast<GlobalNameMapEntry*>(iter.Get());
-    n += entry->SizeOfExcludingThis(aMallocSizeOf);
-  }
-
-  return n;
-}

deleted file mode 100644
--- a/dom/base/nsScriptNameSpaceManager.h
+++ /dev/null
@@ -1,145 +0,0 @@
-/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
-/* vim: set ts=8 sts=2 et sw=2 tw=80: */
-/* 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/. */
-
-#ifndef nsScriptNameSpaceManager_h__
-#define nsScriptNameSpaceManager_h__
-
-#include "mozilla/MemoryReporting.h"
-#include "nsBaseHashtable.h"
-#include "nsIMemoryReporter.h"
-#include "nsIScriptNameSpaceManager.h"
-#include "nsString.h"
-#include "nsID.h"
-#include "PLDHashTable.h"
-#include "nsDOMClassInfo.h"
-#include "nsIObserver.h"
-#include "nsWeakReference.h"
-#include "xpcpublic.h"
-
-struct nsGlobalNameStruct
-{
-  enum nametype {
-    eTypeNotInitialized,
-    eTypeProperty,
-  } mType;
-
-  union {
-    nsCID mCID; // eTypeProperty
-  };
-};
-
-class GlobalNameMapEntry : public PLDHashEntryHdr
-{
-public:
-  // Our hash table ops don't care about the order of these members.
-  nsString mKey;
-  nsGlobalNameStruct mGlobalName;
-
-  size_t SizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const {
-    // Measurement of the following members may be added later if DMD finds it
-    // is worthwhile:
-    // - mGlobalName
-    return mKey.SizeOfExcludingThisIfUnshared(aMallocSizeOf);
-  }
-};
-
-class nsICategoryManager;
-
-class nsScriptNameSpaceManager : public nsIObserver,
-                                 public nsSupportsWeakReference,
-                                 public nsIMemoryReporter
-{
-public:
-  NS_DECL_ISUPPORTS
-  NS_DECL_NSIOBSERVER
-  NS_DECL_NSIMEMORYREPORTER
-
-  nsScriptNameSpaceManager();
-
-  nsresult Init();
-
-  // Returns a nsGlobalNameStruct for aName, or null if one is not
-  // found. The returned nsGlobalNameStruct is only guaranteed to be
-  // valid until the next call to any of the methods in this class.
-  // It also returns a pointer to the string buffer of the classname
-  // in the nsGlobalNameStruct.
-  const nsGlobalNameStruct* LookupName(const nsAString& aName,
-                                       const char16_t **aClassName = nullptr);
-
-  class NameIterator : public PLDHashTable::Iterator
-  {
-  public:
-    typedef PLDHashTable::Iterator Base;
-    explicit NameIterator(PLDHashTable* aTable) : Base(aTable) {}
-    NameIterator(NameIterator&& aOther) : Base(mozilla::Move(aOther.mTable)) {}
-
-    const GlobalNameMapEntry* Get() const
-    {
-      return static_cast<const GlobalNameMapEntry*>(Base::Get());
-    }
-
-  private:
-    NameIterator() = delete;
-    NameIterator(const NameIterator&) = delete;
-    NameIterator& operator=(const NameIterator&) = delete;
-    NameIterator& operator=(const NameIterator&&) = delete;
-  };
-
-  NameIterator GlobalNameIter()    { return NameIterator(&mGlobalNames); }
-
-  size_t SizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf) const;
-
-private:
-  virtual ~nsScriptNameSpaceManager();
-
-  // Adds a new entry to the hash and returns the nsGlobalNameStruct
-  // that aKey will be mapped to. If mType in the returned
-  // nsGlobalNameStruct is != eTypeNotInitialized, an entry for aKey
-  // already existed.
-  nsGlobalNameStruct *AddToHash(const char *aKey,
-                                const char16_t **aClassName = nullptr);
-
-  // Removes an existing entry from the hash.
-  void RemoveFromHash(const nsAString *aKey);
-
-  nsresult FillHash(nsICategoryManager *aCategoryManager,
-                    const char *aCategory);
-
-  /**
-   * Add a new category entry into the hash table.
-   * Only some categories can be added (see the beginning of the definition).
-   * The other ones will be ignored.
-   *
-   * @aCategoryManager Instance of the category manager service.
-   * @aCategory        Category where the entry comes from.
-   * @aEntry           The entry that should be added.
-   */
-  nsresult AddCategoryEntryToHash(nsICategoryManager* aCategoryManager,
-                                  const char* aCategory,
-                                  nsISupports* aEntry);
-
-  /**
-   * Remove an existing category entry from the hash table.
-   * Only some categories can be removed (see the beginning of the definition).
-   * The other ones will be ignored.
-   *
-   * @aCategory        Category where the entry will be removed from.
-   * @aEntry           The entry that should be removed.
-   */
-  nsresult RemoveCategoryEntryFromHash(nsICategoryManager* aCategoryManager,
-                                       const char* aCategory,
-                                       nsISupports* aEntry);
-
-  // common helper for AddCategoryEntryToHash and RemoveCategoryEntryFromHash
-  nsresult OperateCategoryEntryHash(nsICategoryManager* aCategoryManager,
-                                    const char* aCategory,
-                                    nsISupports* aEntry,
-                                    bool aRemove);
-
-  PLDHashTable mGlobalNames;
-};
-
-#endif /* nsScriptNameSpaceManager_h__ */

--- a/js/src/devtools/rootAnalysis/annotations.js
+++ b/js/src/devtools/rootAnalysis/annotations.js
@@ -198,21 +198,16 @@ var ignoreFunctions = {
     // FIXME!
     "NS_DebugBreak": true,
 
     // These are a little overzealous -- these destructors *can* GC if they end
     // up wrapping a pending exception. See bug 898815 for the heavyweight fix.
     "void js::AutoCompartment::~AutoCompartment(int32)" : true,
     "void JSAutoCompartment::~JSAutoCompartment(int32)" : true,
 
-    // The nsScriptNameSpaceManager functions can't actually GC.  They
-    // just use a PLDHashTable which has function pointers, which makes the
-    // analysis think maybe they can.
-    "nsGlobalNameStruct* nsScriptNameSpaceManager::LookupName(nsAString*, uint16**)": true,
-
     // Similar to heap snapshot mock classes, and GTests below. This posts a
     // synchronous runnable when a GTest fails, and we are pretty sure that the
     // particular runnable it posts can't even GC, but the analysis isn't
     // currently smart enough to determine that. In either case, this is (a)
     // only in GTests, and (b) only when the Gtest has already failed. We have
     // static and dynamic checks for no GC in the non-test code, and in the test
     // code we fall back to only the dynamic checks.
     "void test::RingbufferDumper::OnTestPartResult(testing::TestPartResult*)" : true,

--- a/js/xpconnect/src/xpcpublic.h
+++ b/js/xpconnect/src/xpcpublic.h
@@ -24,17 +24,16 @@
 #include "mozilla/fallible.h"
 #include "nsMathUtils.h"
 #include "nsStringBuffer.h"
 #include "mozilla/dom/BindingDeclarations.h"
 #include "mozilla/Preferences.h"
 
 class nsGlobalWindowInner;
 class nsIPrincipal;
-class nsScriptNameSpaceManager;
 class nsIHandleReportCallback;
 
 namespace mozilla {
 namespace dom {
 class Exception;
 }
 }
 

--- a/layout/build/nsLayoutModule.cpp
+++ b/layout/build/nsLayoutModule.cpp
@@ -28,17 +28,16 @@
 #include "nsIDocumentEncoder.h"
 #include "nsIFactory.h"
 #include "nsIIdleService.h"
 #include "nsHTMLStyleSheet.h"
 #include "nsILayoutDebugger.h"
 #include "nsNameSpaceManager.h"
 #include "nsIObserver.h"
 #include "nsIObserverService.h"
-#include "nsIScriptNameSpaceManager.h"
 #include "nsIScriptError.h"
 #include "nsISelection.h"
 #include "nsCaret.h"
 #include "nsPlainTextSerializer.h"
 #include "nsXMLContentSerializer.h"
 #include "nsXHTMLContentSerializer.h"
 #include "nsContentAreaDragDrop.h"
 #include "nsBox.h"
@@ -63,17 +62,16 @@
 
 // view stuff
 #include "nsContentCreatorFunctions.h"
 
 #include "nsHostObjectURI.h"
 #include "nsGlobalWindowCommands.h"
 #include "nsIControllerCommandTable.h"
 #include "nsJSProtocolHandler.h"
-#include "nsScriptNameSpaceManager.h"
 #include "nsIControllerContext.h"
 #include "nsZipArchive.h"
 #include "mozilla/Attributes.h"
 #include "mozilla/dom/DOMRequest.h"
 #include "mozilla/dom/LocalStorageManager.h"
 #include "mozilla/dom/network/UDPSocketChild.h"
 #include "mozilla/dom/quota/QuotaManagerService.h"
 #include "mozilla/dom/ServiceWorkerManager.h"