diff --git a/dom/events/EventListenerManager.cpp b/dom/events/EventListenerManager.cpp
index 7628c1a26087..cf29b35600dc 100644
--- a/dom/events/EventListenerManager.cpp
+++ b/dom/events/EventListenerManager.cpp
@@ -1040,7 +1040,7 @@ nsresult EventListenerManager::CompileEventHandlerInternal(
 
   RefPtr<ScriptFetchOptions> fetchOptions = new ScriptFetchOptions(
       CORS_NONE, aElement->OwnerDoc()->GetReferrerPolicy(), aElement,
-      aElement->OwnerDoc()->NodePrincipal(), nullptr);
+      aElement->OwnerDoc()->NodePrincipal());
 
   RefPtr<EventScript> eventScript = new EventScript(fetchOptions, uri);
 
diff --git a/dom/locales/en-US/chrome/dom/dom.properties b/dom/locales/en-US/chrome/dom/dom.properties
index 67f5fe84a5bd..3ef8881e3f00 100644
--- a/dom/locales/en-US/chrome/dom/dom.properties
+++ b/dom/locales/en-US/chrome/dom/dom.properties
@@ -317,7 +317,6 @@ ModuleSourceMalformed=Module source URI is malformed: “%S”.
 # LOCALIZATION NOTE: Do not translate "<script>".
 ScriptSourceNotAllowed=<script> source URI is not allowed in this document: “%S”.
 ModuleSourceNotAllowed=Module source URI is not allowed in this document: “%S”.
-WebExtContentScriptModuleSourceNotAllowed=WebExtension content scripts may only load modules with moz-extension URLs and not: “%S”.
 ModuleResolveFailure=Error resolving module specifier “%S”. Relative module specifiers must start with “./”, “../” or “/”.
 # LOCALIZATION NOTE: %1$S is the invalid property value and %2$S is the property name.
 InvalidKeyframePropertyValue=Keyframe property value “%1$S” is invalid according to the syntax for “%2$S”.
diff --git a/dom/script/ModuleLoadRequest.cpp b/dom/script/ModuleLoadRequest.cpp
index 925f8babe3c7..c2771e6d46a6 100644
--- a/dom/script/ModuleLoadRequest.cpp
+++ b/dom/script/ModuleLoadRequest.cpp
@@ -149,7 +149,7 @@ void ModuleLoadRequest::ModuleLoaded() {
 
   LOG(("ScriptLoadRequest (%p): Module loaded", this));
 
-  mModuleScript = mLoader->GetFetchedModule(mURI, GetWebExtGlobal());
+  mModuleScript = mLoader->GetFetchedModule(mURI);
   if (!mModuleScript || mModuleScript->HasParseError()) {
     ModuleErrored();
     return;
diff --git a/dom/script/ModuleLoadRequest.h b/dom/script/ModuleLoadRequest.h
index 19a314a9c322..8faff57cac74 100644
--- a/dom/script/ModuleLoadRequest.h
+++ b/dom/script/ModuleLoadRequest.h
@@ -8,10 +8,10 @@
 #define mozilla_dom_ModuleLoadRequest_h
 
 #include "ScriptLoadRequest.h"
-#include "mozilla/MozPromise.h"
 #include "js/RootingAPI.h"
 #include "js/Value.h"
 #include "nsURIHashKey.h"
+#include "mozilla/MozPromise.h"
 #include "nsTHashtable.h"
 
 namespace mozilla {
diff --git a/dom/script/ModuleMapKey.cpp b/dom/script/ModuleMapKey.cpp
deleted file mode 100644
index dc5779193c88..000000000000
--- a/dom/script/ModuleMapKey.cpp
+++ /dev/null
@@ -1,38 +0,0 @@
-/* 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 "ModuleMapKey.h"
-
-using namespace mozilla::dom;
-
-ModuleMapKey::ModuleMapKey(const nsIURI* aURI, nsIGlobalObject* aWebExtGlobal)
-    : nsURIHashKey(aURI), mWebExtGlobal(aWebExtGlobal) {}
-
-ModuleMapKey::ModuleMapKey(const ModuleMapKey* aKey)
-    : nsURIHashKey(aKey->mKey) {
-  *this = *aKey;
-}
-
-ModuleMapKey::ModuleMapKey(ModuleMapKey&& aToMove) noexcept
-    : nsURIHashKey(std::move(aToMove)) {
-  mWebExtGlobal = std::move(aToMove.mWebExtGlobal);
-}
-
-bool ModuleMapKey::KeyEquals(KeyTypePointer aOther) const {
-  if (mWebExtGlobal != aOther->mWebExtGlobal) {
-    return false;
-  }
-
-  return nsURIHashKey::KeyEquals(
-      static_cast<const nsURIHashKey*>(aOther)->GetKey());
-}
-
-// static
-PLDHashNumber ModuleMapKey::HashKey(KeyTypePointer aKey) {
-  PLDHashNumber hash = nsURIHashKey::HashKey(aKey->mKey);
-  // XXX This seems wrong.
-  hash =
-      AddToHash(hash, reinterpret_cast<uintptr_t>(aKey->mWebExtGlobal.get()));
-  return hash;
-}
diff --git a/dom/script/ModuleMapKey.h b/dom/script/ModuleMapKey.h
deleted file mode 100644
index d3c54f4c5ba5..000000000000
--- a/dom/script/ModuleMapKey.h
+++ /dev/null
@@ -1,47 +0,0 @@
-/* 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 ModuleMapKey_h__
-#define ModuleMapKey_h__
-
-#include "nsURIHashKey.h"
-#include "nsIGlobalObject.h"
-
-namespace mozilla::dom {
-
-class ModuleMapKey : public nsURIHashKey {
- public:
-  using KeyType = ModuleMapKey&;
-  using KeyTypePointer = const ModuleMapKey*;
-
-  ModuleMapKey() = default;
-  ModuleMapKey(const nsIURI* aURI, nsIGlobalObject* aWebExtGlobal);
-  explicit ModuleMapKey(const ModuleMapKey* aKey);
-  ModuleMapKey(ModuleMapKey&& aToMove) noexcept;
-
-  ModuleMapKey& operator=(const ModuleMapKey& aOther) = default;
-
-  KeyType GetKey() { return *this; }
-  KeyTypePointer GetKeyPointer() const { return this; }
-  static KeyTypePointer KeyToPointer(KeyType aKey) { return &aKey; }
-
-  bool KeyEquals(KeyTypePointer aOther) const;
-  static PLDHashNumber HashKey(KeyTypePointer aKey);
-
-  nsCOMPtr<nsIGlobalObject> mWebExtGlobal;
-};
-
-inline void ImplCycleCollectionUnlink(ModuleMapKey& aField) {
-  ImplCycleCollectionUnlink(aField.mWebExtGlobal);
-}
-
-inline void ImplCycleCollectionTraverse(
-    nsCycleCollectionTraversalCallback& aCallback, ModuleMapKey& aField,
-    const char* aName, uint32_t aFlags = 0) {
-  ImplCycleCollectionTraverse(aCallback, aField.mWebExtGlobal, aName, aFlags);
-}
-
-}  // namespace mozilla::dom
-
-#endif
diff --git a/dom/script/ScriptLoadRequest.cpp b/dom/script/ScriptLoadRequest.cpp
index a17b816aee77..08c72a118c46 100644
--- a/dom/script/ScriptLoadRequest.cpp
+++ b/dom/script/ScriptLoadRequest.cpp
@@ -27,8 +27,7 @@ namespace dom {
 // ScriptFetchOptions
 //////////////////////////////////////////////////////////////
 
-NS_IMPL_CYCLE_COLLECTION(ScriptFetchOptions, mElement, mTriggeringPrincipal,
-                         mWebExtGlobal)
+NS_IMPL_CYCLE_COLLECTION(ScriptFetchOptions, mElement, mTriggeringPrincipal)
 
 NS_IMPL_CYCLE_COLLECTION_ROOT_NATIVE(ScriptFetchOptions, AddRef)
 NS_IMPL_CYCLE_COLLECTION_UNROOT_NATIVE(ScriptFetchOptions, Release)
@@ -36,14 +35,12 @@ NS_IMPL_CYCLE_COLLECTION_UNROOT_NATIVE(ScriptFetchOptions, Release)
 ScriptFetchOptions::ScriptFetchOptions(mozilla::CORSMode aCORSMode,
                                        ReferrerPolicy aReferrerPolicy,
                                        Element* aElement,
-                                       nsIPrincipal* aTriggeringPrincipal,
-                                       nsIGlobalObject* aWebExtGlobal)
+                                       nsIPrincipal* aTriggeringPrincipal)
     : mCORSMode(aCORSMode),
       mReferrerPolicy(aReferrerPolicy),
       mIsPreload(false),
       mElement(aElement),
-      mTriggeringPrincipal(aTriggeringPrincipal),
-      mWebExtGlobal(aWebExtGlobal) {
+      mTriggeringPrincipal(aTriggeringPrincipal) {
   MOZ_ASSERT(mTriggeringPrincipal);
 }
 
@@ -62,7 +59,6 @@ NS_IMPL_CYCLE_COLLECTING_RELEASE(ScriptLoadRequest)
 NS_IMPL_CYCLE_COLLECTION_CLASS(ScriptLoadRequest)
 
 NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(ScriptLoadRequest)
-  // XXX missing mLoadBlockedDocument ?
   NS_IMPL_CYCLE_COLLECTION_UNLINK(mFetchOptions, mCacheInfo)
   tmp->mScript = nullptr;
   if (Runnable* runnable = tmp->mRunnable.exchange(nullptr)) {
diff --git a/dom/script/ScriptLoadRequest.h b/dom/script/ScriptLoadRequest.h
index 203529b579ed..7ee10fa96d95 100644
--- a/dom/script/ScriptLoadRequest.h
+++ b/dom/script/ScriptLoadRequest.h
@@ -22,7 +22,6 @@
 #include "mozilla/Vector.h"
 #include "nsCOMPtr.h"
 #include "nsCycleCollectionParticipant.h"
-#include "nsIGlobalObject.h"
 #include "nsIScriptElement.h"
 #include "ScriptKind.h"
 
@@ -56,17 +55,13 @@ class ScriptFetchOptions {
 
   ScriptFetchOptions(mozilla::CORSMode aCORSMode,
                      enum ReferrerPolicy aReferrerPolicy, Element* aElement,
-                     nsIPrincipal* aTriggeringPrincipal,
-                     nsIGlobalObject* aWebExtGlobal);
+                     nsIPrincipal* aTriggeringPrincipal);
 
   const mozilla::CORSMode mCORSMode;
   const enum ReferrerPolicy mReferrerPolicy;
   bool mIsPreload;
   nsCOMPtr<Element> mElement;
   nsCOMPtr<nsIPrincipal> mTriggeringPrincipal;
-  // Global that initiated this request, when using a WebExtension
-  // content-script.
-  nsCOMPtr<nsIGlobalObject> mWebExtGlobal;
 };
 
 /*
@@ -263,13 +258,6 @@ class ScriptLoadRequest
     return mFetchOptions->mTriggeringPrincipal;
   }
 
-  // This will return nullptr in most cases,
-  // unless this is a module being imported by a WebExtension content script.
-  // In that case it's the Sandbox global executing that code.
-  nsIGlobalObject* GetWebExtGlobal() const {
-    return mFetchOptions->mWebExtGlobal;
-  }
-
   // Make this request a preload (speculative) request.
   void SetIsPreloadRequest() {
     MOZ_ASSERT(!GetScriptElement());
diff --git a/dom/script/ScriptLoader.cpp b/dom/script/ScriptLoader.cpp
index 8ca2dab5f26a..80bf62ba625b 100644
--- a/dom/script/ScriptLoader.cpp
+++ b/dom/script/ScriptLoader.cpp
@@ -151,57 +151,6 @@ inline void ImplCycleCollectionTraverse(
   ImplCycleCollectionTraverse(aCallback, aField.mRequest, aName, aFlags);
 }
 
-//////////////////////////////////////////////////////////////
-// ScriptLoader::mFetchingModules / ScriptLoader::mFetchingModules
-//////////////////////////////////////////////////////////////
-
-inline void ImplCycleCollectionUnlink(
-    nsRefPtrHashtable<ModuleMapKey,
-                      mozilla::GenericNonExclusivePromise::Private>& aField) {
-  for (auto iter = aField.Iter(); !iter.Done(); iter.Next()) {
-    ImplCycleCollectionUnlink(iter.Key());
-
-    RefPtr<GenericNonExclusivePromise::Private> promise = iter.UserData();
-    if (promise) {
-      promise->Reject(NS_ERROR_ABORT, __func__);
-    }
-  }
-
-  aField.Clear();
-}
-
-inline void ImplCycleCollectionTraverse(
-    nsCycleCollectionTraversalCallback& aCallback,
-    nsRefPtrHashtable<ModuleMapKey,
-                      mozilla::GenericNonExclusivePromise::Private>& aField,
-    const char* aName, uint32_t aFlags = 0) {
-  for (auto iter = aField.Iter(); !iter.Done(); iter.Next()) {
-    ImplCycleCollectionTraverse(aCallback, iter.Key(), "mFetchingModules key",
-                                aFlags);
-  }
-}
-
-inline void ImplCycleCollectionUnlink(
-    nsRefPtrHashtable<ModuleMapKey, ModuleScript>& aField) {
-  for (auto iter = aField.Iter(); !iter.Done(); iter.Next()) {
-    ImplCycleCollectionUnlink(iter.Key());
-  }
-
-  aField.Clear();
-}
-
-inline void ImplCycleCollectionTraverse(
-    nsCycleCollectionTraversalCallback& aCallback,
-    nsRefPtrHashtable<ModuleMapKey, ModuleScript>& aField, const char* aName,
-    uint32_t aFlags = 0) {
-  for (auto iter = aField.Iter(); !iter.Done(); iter.Next()) {
-    ImplCycleCollectionTraverse(aCallback, iter.Key(), "mFetchedModules key",
-                                aFlags);
-    CycleCollectionNoteChild(aCallback, iter.UserData(), "mFetchedModules data",
-                             aFlags);
-  }
-}
-
 //////////////////////////////////////////////////////////////
 // ScriptLoader
 //////////////////////////////////////////////////////////////
@@ -213,8 +162,7 @@ NS_IMPL_CYCLE_COLLECTION(ScriptLoader, mNonAsyncExternalScriptInsertedRequests,
                          mLoadingAsyncRequests, mLoadedAsyncRequests,
                          mDeferRequests, mXSLTRequests, mDynamicImportRequests,
                          mParserBlockingRequest, mBytecodeEncodingQueue,
-                         mPreloads, mPendingChildLoaders, mFetchedModules,
-                         mFetchingModules)
+                         mPreloads, mPendingChildLoaders, mFetchedModules)
 
 NS_IMPL_CYCLE_COLLECTING_ADDREF(ScriptLoader)
 NS_IMPL_CYCLE_COLLECTING_RELEASE(ScriptLoader)
@@ -493,23 +441,25 @@ bool ScriptLoader::IsAboutPageLoadingChromeURI(ScriptLoadRequest* aRequest,
   return true;
 }
 
-bool ScriptLoader::ModuleMapContainsURL(nsIURI* aURL,
-                                        nsIGlobalObject* aGlobal) const {
+bool ScriptLoader::ModuleMapContainsURL(nsIURI* aURL) const {
   // Returns whether we have fetched, or are currently fetching, a module script
   // for a URL.
-  ModuleMapKey key(aURL, aGlobal);
-  return mFetchingModules.Contains(key) || mFetchedModules.Contains(key);
+  return mFetchingModules.Contains(aURL) || mFetchedModules.Contains(aURL);
+}
+
+bool ScriptLoader::IsFetchingModule(ModuleLoadRequest* aRequest) const {
+  bool fetching = mFetchingModules.Contains(aRequest->mURI);
+  MOZ_ASSERT_IF(fetching, !mFetchedModules.Contains(aRequest->mURI));
+  return fetching;
 }
 
 void ScriptLoader::SetModuleFetchStarted(ModuleLoadRequest* aRequest) {
   // Update the module map to indicate that a module is currently being fetched.
 
   MOZ_ASSERT(aRequest->IsLoading());
-  MOZ_ASSERT(
-      !ModuleMapContainsURL(aRequest->mURI, aRequest->GetWebExtGlobal()));
-  ModuleMapKey key(aRequest->mURI, aRequest->GetWebExtGlobal());
+  MOZ_ASSERT(!ModuleMapContainsURL(aRequest->mURI));
   mFetchingModules.InsertOrUpdate(
-      key, RefPtr<GenericNonExclusivePromise::Private>{});
+      aRequest->mURI, RefPtr<GenericNonExclusivePromise::Private>{});
 }
 
 void ScriptLoader::SetModuleFetchFinishedAndResumeWaitingRequests(
@@ -525,18 +475,14 @@ void ScriptLoader::SetModuleFetchFinishedAndResumeWaitingRequests(
        "%u)",
        aRequest, aRequest->mModuleScript.get(), unsigned(aResult)));
 
-  ModuleMapKey key(aRequest->mURI, aRequest->GetWebExtGlobal());
   RefPtr<GenericNonExclusivePromise::Private> promise;
-  if (!mFetchingModules.Remove(key, getter_AddRefs(promise))) {
-    LOG(("ScriptLoadRequest (%p): Key not found in mFetchingModules",
-         aRequest));
-    return;
-  }
+  MOZ_ALWAYS_TRUE(
+      mFetchingModules.Remove(aRequest->mURI, getter_AddRefs(promise)));
 
   RefPtr<ModuleScript> moduleScript(aRequest->mModuleScript);
   MOZ_ASSERT(NS_FAILED(aResult) == !moduleScript);
 
-  mFetchedModules.InsertOrUpdate(key, RefPtr{moduleScript});
+  mFetchedModules.InsertOrUpdate(aRequest->mURI, RefPtr{moduleScript});
 
   if (promise) {
     if (moduleScript) {
@@ -550,11 +496,10 @@ void ScriptLoader::SetModuleFetchFinishedAndResumeWaitingRequests(
 }
 
 RefPtr<GenericNonExclusivePromise> ScriptLoader::WaitForModuleFetch(
-    nsIURI* aURL, nsIGlobalObject* aGlobal) {
-  MOZ_ASSERT(ModuleMapContainsURL(aURL, aGlobal));
+    nsIURI* aURL) {
+  MOZ_ASSERT(ModuleMapContainsURL(aURL));
 
-  ModuleMapKey key(aURL, aGlobal);
-  if (auto entry = mFetchingModules.Lookup(key)) {
+  if (auto entry = mFetchingModules.Lookup(aURL)) {
     if (!entry.Data()) {
       entry.Data() = new GenericNonExclusivePromise::Private(__func__);
     }
@@ -562,7 +507,7 @@ RefPtr<GenericNonExclusivePromise> ScriptLoader::WaitForModuleFetch(
   }
 
   RefPtr<ModuleScript> ms;
-  MOZ_ALWAYS_TRUE(mFetchedModules.Get(key, getter_AddRefs(ms)));
+  MOZ_ALWAYS_TRUE(mFetchedModules.Get(aURL, getter_AddRefs(ms)));
   if (!ms) {
     return GenericNonExclusivePromise::CreateAndReject(NS_ERROR_FAILURE,
                                                        __func__);
@@ -571,17 +516,15 @@ RefPtr<GenericNonExclusivePromise> ScriptLoader::WaitForModuleFetch(
   return GenericNonExclusivePromise::CreateAndResolve(true, __func__);
 }
 
-ModuleScript* ScriptLoader::GetFetchedModule(nsIURI* aURL,
-                                             nsIGlobalObject* aGlobal) const {
+ModuleScript* ScriptLoader::GetFetchedModule(nsIURI* aURL) const {
   if (LOG_ENABLED()) {
     nsAutoCString url;
     aURL->GetAsciiSpec(url);
-    LOG(("GetFetchedModule %s %p", url.get(), aGlobal));
+    LOG(("GetFetchedModule %s", url.get()));
   }
 
   bool found;
-  ModuleMapKey key(aURL, aGlobal);
-  ModuleScript* ms = mFetchedModules.GetWeak(key, &found);
+  ModuleScript* ms = mFetchedModules.GetWeak(aURL, &found);
   MOZ_ASSERT(found);
   return ms;
 }
@@ -619,23 +562,14 @@ nsresult ScriptLoader::CreateModuleScript(ModuleLoadRequest* aRequest) {
 
   LOG(("ScriptLoadRequest (%p): Create module script", aRequest));
 
-  nsCOMPtr<nsIGlobalObject> globalObject;
-  nsCOMPtr<nsIScriptContext> context;
-  if (aRequest->GetWebExtGlobal()) {
-    globalObject = aRequest->GetWebExtGlobal();
-  } else {
-    nsCOMPtr<nsIScriptGlobalObject> scriptGlobal =
-        GetScriptGlobalObject(WebExtGlobal::Handled);
-    if (!scriptGlobal) {
-      return NS_ERROR_FAILURE;
-    }
+  nsCOMPtr<nsIScriptGlobalObject> globalObject = GetScriptGlobalObject();
+  if (!globalObject) {
+    return NS_ERROR_FAILURE;
+  }
 
-    context = scriptGlobal->GetScriptContext();
-    if (!context) {
-      return NS_ERROR_FAILURE;
-    }
-
-    globalObject = scriptGlobal;
+  nsCOMPtr<nsIScriptContext> context = globalObject->GetScriptContext();
+  if (!context) {
+    return NS_ERROR_FAILURE;
   }
 
   nsAutoMicroTask mt;
@@ -644,11 +578,8 @@ nsresult ScriptLoader::CreateModuleScript(ModuleLoadRequest* aRequest) {
 
   AutoEntryScript aes(globalObject, "CompileModule", true);
 
-  bool oldProcessingScriptTag = false;
-  if (context) {
-    oldProcessingScriptTag = context->GetProcessingScriptTag();
-    context->SetProcessingScriptTag(true);
-  }
+  bool oldProcessingScriptTag = context->GetProcessingScriptTag();
+  context->SetProcessingScriptTag(true);
 
   nsresult rv;
   {
@@ -713,9 +644,7 @@ nsresult ScriptLoader::CreateModuleScript(ModuleLoadRequest* aRequest) {
     }
   }
 
-  if (context) {
-    context->SetProcessingScriptTag(oldProcessingScriptTag);
-  }
+  context->SetProcessingScriptTag(oldProcessingScriptTag);
 
   LOG(("ScriptLoadRequest (%p):   module script == %p", aRequest,
        aRequest->mModuleScript.get()));
@@ -880,7 +809,6 @@ void ScriptLoader::StartFetchingModuleDependencies(
   nsCOMArray<nsIURI> urls;
   nsresult rv = ResolveRequestedModules(aRequest, &urls);
   if (NS_FAILED(rv)) {
-    aRequest->mModuleScript = nullptr;
     aRequest->ModuleErrored();
     return;
   }
@@ -950,8 +878,6 @@ RefPtr<GenericPromise> ScriptLoader::StartFetchingModuleAndDependencies(
     MOZ_ASSERT(!childRequest->mModuleScript);
     LOG(("ScriptLoadRequest (%p):   rejecting %p", aParent,
          &childRequest->mReady));
-
-    ReportErrorToConsole(childRequest, rv);
     childRequest->mReady.Reject(rv, __func__);
     return ready;
   }
@@ -974,13 +900,8 @@ static ScriptLoader* GetCurrentScriptLoader(JSContext* aCx) {
     return nullptr;
   }
 
-  nsGlobalWindowInner* innerWindow = nullptr;
-  if (nsCOMPtr<nsPIDOMWindowInner> win = do_QueryInterface(global)) {
-    innerWindow = nsGlobalWindowInner::Cast(win);
-  } else {
-    innerWindow = xpc::SandboxWindowOrNull(object, aCx);
-  }
-
+  nsCOMPtr<nsPIDOMWindowInner> win = do_QueryInterface(global);
+  nsGlobalWindowInner* innerWindow = nsGlobalWindowInner::Cast(win);
   if (!innerWindow) {
     return nullptr;
   }
@@ -1054,19 +975,9 @@ void ScriptLoader::ResolveImportedModule(
   // previously successful with these same two arguments.
   MOZ_ASSERT(uri, "Failed to resolve previously-resolved module specifier");
 
-  // Use sandboxed global when doing a WebExtension content-script load.
-  nsCOMPtr<nsIGlobalObject> global;
-  if (BasePrincipal::Cast(nsContentUtils::SubjectPrincipal(aCx))
-          ->ContentScriptAddonPolicy()) {
-    global = xpc::CurrentNativeGlobal(aCx);
-    MOZ_ASSERT(global);
-    MOZ_ASSERT(
-        xpc::IsWebExtensionContentScriptSandbox(global->GetGlobalJSObject()));
-  }
-
   // Let resolved module script be moduleMap[url]. (This entry must exist for us
   // to have gotten to this point.)
-  ModuleScript* ms = loader->GetFetchedModule(uri, global);
+  ModuleScript* ms = loader->GetFetchedModule(uri);
   MOZ_ASSERT(ms, "Resolved module not found in module map");
   MOZ_ASSERT(!ms->HasParseError());
   MOZ_ASSERT(ms->ModuleRecord());
@@ -1139,24 +1050,9 @@ bool HostImportModuleDynamically(JSContext* aCx,
     // triggers an inline event handler, as there is no active script
     // there.
     Document* document = loader->GetDocument();
-
-    // Use the document's principal for all loads, except WebExtension
-    // content-scripts.
-    // Only remember the global for content-scripts as well.
-    nsCOMPtr<nsIPrincipal> principal = nsContentUtils::SubjectPrincipal(aCx);
-    nsCOMPtr<nsIGlobalObject> global = xpc::CurrentNativeGlobal(aCx);
-    if (!BasePrincipal::Cast(principal)->ContentScriptAddonPolicy()) {
-      principal = document->NodePrincipal();
-      MOZ_ASSERT(global);
-      global = nullptr;  // Null global is the usual case for most loads.
-    } else {
-      MOZ_ASSERT(
-          xpc::IsWebExtensionContentScriptSandbox(global->GetGlobalJSObject()));
-    }
-
     options = new ScriptFetchOptions(mozilla::CORS_NONE,
                                      document->GetReferrerPolicy(), nullptr,
-                                     principal, global);
+                                     document->NodePrincipal());
     baseURL = document->GetDocBaseURI();
   }
 
@@ -1174,7 +1070,6 @@ void ScriptLoader::StartDynamicImport(ModuleLoadRequest* aRequest) {
 
   nsresult rv = StartLoad(aRequest);
   if (NS_FAILED(rv)) {
-    ReportErrorToConsole(aRequest, rv);
     FinishDynamicImportAndReject(aRequest, rv);
   }
 }
@@ -1494,20 +1389,12 @@ nsresult ScriptLoader::StartLoad(ScriptLoadRequest* aRequest) {
   }
 
   if (aRequest->IsModuleRequest()) {
-    // To prevent dynamic code execution, content scripts can only
-    // load moz-extension URLs.
-    nsCOMPtr<nsIPrincipal> principal = aRequest->TriggeringPrincipal();
-    if (BasePrincipal::Cast(principal)->ContentScriptAddonPolicy() &&
-        !aRequest->mURI->SchemeIs("moz-extension")) {
-      return NS_ERROR_DOM_WEBEXT_CONTENT_SCRIPT_URI;
-    }
-
     // Check whether the module has been fetched or is currently being fetched,
     // and if so wait for it rather than starting a new fetch.
     ModuleLoadRequest* request = aRequest->AsModuleRequest();
-    if (ModuleMapContainsURL(request->mURI, aRequest->GetWebExtGlobal())) {
+    if (ModuleMapContainsURL(request->mURI)) {
       LOG(("ScriptLoadRequest (%p): Waiting for module fetch", aRequest));
-      WaitForModuleFetch(request->mURI, aRequest->GetWebExtGlobal())
+      WaitForModuleFetch(request->mURI)
           ->Then(GetMainThreadSerialEventTarget(), __func__, request,
                  &ModuleLoadRequest::ModuleLoaded,
                  &ModuleLoadRequest::LoadFailed);
@@ -1582,9 +1469,7 @@ nsresult ScriptLoader::StartLoad(ScriptLoadRequest* aRequest) {
     }
   }
 
-  // Module requests aren't cached, so ignore WebExtGlobal here.
-  nsCOMPtr<nsIScriptGlobalObject> globalObject =
-      GetScriptGlobalObject(WebExtGlobal::Ignore);
+  nsCOMPtr<nsIScriptGlobalObject> globalObject = GetScriptGlobalObject();
   if (!globalObject) {
     return NS_ERROR_FAILURE;
   }
@@ -1599,8 +1484,6 @@ nsresult ScriptLoader::StartLoad(ScriptLoadRequest* aRequest) {
       !js::GlobalHasInstrumentation(globalObject->GetGlobalJSObject()) &&
       // Bug 1436400: no bytecode cache support for modules yet.
       !aRequest->IsModuleRequest()) {
-    MOZ_ASSERT(!aRequest->GetWebExtGlobal(),
-               "Can not bytecode cache WebExt code");
     if (!aRequest->IsLoadingSource()) {
       // Inform the HTTP cache that we prefer to have information coming from
       // the bytecode cache instead of the sources, if such entry is already
@@ -1792,7 +1675,7 @@ ScriptLoadRequest* ScriptLoader::CreateLoadRequest(
   nsIURI* referrer = mDocument->GetDocumentURIAsReferrer();
   nsCOMPtr<Element> domElement = do_QueryInterface(aElement);
   ScriptFetchOptions* fetchOptions = new ScriptFetchOptions(
-      aCORSMode, aReferrerPolicy, domElement, aTriggeringPrincipal, nullptr);
+      aCORSMode, aReferrerPolicy, domElement, aTriggeringPrincipal);
 
   if (aKind == ScriptKind::eClassic) {
     return new ScriptLoadRequest(aKind, aURI, fetchOptions, aIntegrity,
@@ -2510,7 +2393,7 @@ nsresult ScriptLoader::AttemptAsyncScriptCompile(ScriptLoadRequest* aRequest,
     return NS_OK;
   }
 
-  nsCOMPtr<nsIGlobalObject> globalObject = GetGlobalForRequest(aRequest);
+  nsCOMPtr<nsIScriptGlobalObject> globalObject = GetScriptGlobalObject();
   if (!globalObject) {
     return NS_ERROR_FAILURE;
   }
@@ -2855,18 +2738,7 @@ void ScriptLoader::FireScriptEvaluated(nsresult aResult,
   aRequest->FireScriptEvaluated(aResult);
 }
 
-already_AddRefed<nsIGlobalObject> ScriptLoader::GetGlobalForRequest(
-    ScriptLoadRequest* aRequest) {
-  if (aRequest->GetWebExtGlobal()) {
-    nsCOMPtr<nsIGlobalObject> global = aRequest->GetWebExtGlobal();
-    return global.forget();
-  }
-
-  return GetScriptGlobalObject(WebExtGlobal::Handled);
-}
-
-already_AddRefed<nsIScriptGlobalObject> ScriptLoader::GetScriptGlobalObject(
-    WebExtGlobal) {
+already_AddRefed<nsIScriptGlobalObject> ScriptLoader::GetScriptGlobalObject() {
   if (!mDocument) {
     return nullptr;
   }
@@ -3081,28 +2953,17 @@ nsresult ScriptLoader::EvaluateScript(ScriptLoadRequest* aRequest) {
     }
   }
 
-  nsCOMPtr<nsIGlobalObject> globalObject;
-  nsCOMPtr<nsIScriptContext> context;
-  if (aRequest->GetWebExtGlobal()) {
-    // Executing a module from a WebExtension content-script.
-    globalObject = aRequest->GetWebExtGlobal();
-  } else {
-    // Otherwise we have to ensure that there is a nsIScriptContext.
-    nsCOMPtr<nsIScriptGlobalObject> scriptGlobal =
-        GetScriptGlobalObject(WebExtGlobal::Handled);
-    if (!scriptGlobal) {
-      return NS_ERROR_FAILURE;
-    }
+  nsCOMPtr<nsIScriptGlobalObject> globalObject = GetScriptGlobalObject();
+  if (!globalObject) {
+    return NS_ERROR_FAILURE;
+  }
 
-    // Make sure context is a strong reference since we access it after
-    // we've executed a script, which may cause all other references to
-    // the context to go away.
-    context = scriptGlobal->GetScriptContext();
-    if (!context) {
-      return NS_ERROR_FAILURE;
-    }
-
-    globalObject = scriptGlobal;
+  // Make sure context is a strong reference since we access it after
+  // we've executed a script, which may cause all other references to
+  // the context to go away.
+  nsCOMPtr<nsIScriptContext> context = globalObject->GetScriptContext();
+  if (!context) {
+    return NS_ERROR_FAILURE;
   }
 
 #ifdef MOZ_GECKO_PROFILER
@@ -3119,10 +2980,7 @@ nsresult ScriptLoader::EvaluateScript(ScriptLoadRequest* aRequest) {
   JSContext* cx = aes.cx();
   JS::Rooted<JSObject*> global(cx, globalObject->GetGlobalJSObject());
 
-  Maybe<AutoSetProcessingScriptTag> setProcessingScriptTag;
-  if (context) {
-    setProcessingScriptTag.emplace(context);
-  }
+  AutoSetProcessingScriptTag setProcessingScriptTag(context);
 
   nsresult rv;
   {
@@ -3458,9 +3316,7 @@ void ScriptLoader::EncodeBytecode() {
     return;
   }
 
-  // Should not be encoding modules at all.
-  nsCOMPtr<nsIScriptGlobalObject> globalObject =
-      GetScriptGlobalObject(WebExtGlobal::Ignore);
+  nsCOMPtr<nsIScriptGlobalObject> globalObject = GetScriptGlobalObject();
   if (!globalObject) {
     GiveUpBytecodeEncoding();
     return;
@@ -3478,8 +3334,6 @@ void ScriptLoader::EncodeBytecode() {
   RefPtr<ScriptLoadRequest> request;
   while (!mBytecodeEncodingQueue.isEmpty()) {
     request = mBytecodeEncodingQueue.StealFirst();
-    MOZ_ASSERT(!request->IsModuleRequest());
-    MOZ_ASSERT(!request->GetWebExtGlobal(), "Not handling global above");
     EncodeRequestBytecode(aes.cx(), request);
     request->mScriptBytecode.clearAndFree();
     request->DropBytecodeCacheReferences();
@@ -3567,8 +3421,7 @@ void ScriptLoader::GiveUpBytecodeEncoding() {
   // would not keep a large buffer around.  If we cannot, we fallback on the
   // removal of all request from the current list and these large buffers would
   // be removed at the same time as the source object.
-  nsCOMPtr<nsIScriptGlobalObject> globalObject =
-      GetScriptGlobalObject(WebExtGlobal::Ignore);
+  nsCOMPtr<nsIScriptGlobalObject> globalObject = GetScriptGlobalObject();
   AutoAllowLegacyScriptExecution exemption;
   Maybe<AutoEntryScript> aes;
 
@@ -3584,8 +3437,6 @@ void ScriptLoader::GiveUpBytecodeEncoding() {
     LOG(("ScriptLoadRequest (%p): Cannot serialize bytecode", request.get()));
     TRACE_FOR_TEST_NONE(request->GetScriptElement(),
                         "scriptloader_bytecode_failed");
-    MOZ_ASSERT(!request->IsModuleRequest());
-    MOZ_ASSERT(!request->GetWebExtGlobal());
 
     if (aes.isSome()) {
       JS::RootedScript script(aes->cx(), request->mScript);
@@ -3971,9 +3822,6 @@ void ScriptLoader::ReportErrorToConsole(ScriptLoadRequest* aRequest,
     message = isScript ? "ScriptSourceMalformed" : "ModuleSourceMalformed";
   } else if (aResult == NS_ERROR_DOM_BAD_URI) {
     message = isScript ? "ScriptSourceNotAllowed" : "ModuleSourceNotAllowed";
-  } else if (aResult == NS_ERROR_DOM_WEBEXT_CONTENT_SCRIPT_URI) {
-    MOZ_ASSERT(!isScript);
-    message = "WebExtContentScriptModuleSourceNotAllowed";
   } else if (net::UrlClassifierFeatureFactory::IsClassifierBlockingErrorCode(
                  aResult)) {
     // Blocking classifier error codes already show their own console messages.
diff --git a/dom/script/ScriptLoader.h b/dom/script/ScriptLoader.h
index a3644f9f53c5..58cb353b94bd 100644
--- a/dom/script/ScriptLoader.h
+++ b/dom/script/ScriptLoader.h
@@ -24,7 +24,6 @@
 #include "mozilla/MaybeOneOf.h"
 #include "mozilla/MozPromise.h"
 #include "ScriptKind.h"
-#include "ModuleMapKey.h"
 
 class nsCycleCollectionTraversalCallback;
 class nsIChannel;
@@ -627,16 +626,7 @@ class ScriptLoader final : public nsISupports {
 
   void GiveUpBytecodeEncoding();
 
-  already_AddRefed<nsIGlobalObject> GetGlobalForRequest(
-      ScriptLoadRequest* aRequest);
-
-  // This is a marker class to ensure proper handling of requests with a
-  // WebExtGlobal.
-  enum class WebExtGlobal { Ignore, Handled };
-
-  already_AddRefed<nsIScriptGlobalObject> GetScriptGlobalObject(
-      WebExtGlobal aWebExtGlobal);
-
+  already_AddRefed<nsIScriptGlobalObject> GetScriptGlobalObject();
   nsresult FillCompileOptionsForRequest(const mozilla::dom::AutoJSAPI& jsapi,
                                         ScriptLoadRequest* aRequest,
                                         JS::Handle<JSObject*> aScopeChain,
@@ -668,10 +658,11 @@ class ScriptLoader final : public nsISupports {
   void SetModuleFetchFinishedAndResumeWaitingRequests(
       ModuleLoadRequest* aRequest, nsresult aResult);
 
-  bool ModuleMapContainsURL(nsIURI* aURL, nsIGlobalObject* aGlobal) const;
-  RefPtr<mozilla::GenericNonExclusivePromise> WaitForModuleFetch(
-      nsIURI* aURL, nsIGlobalObject* aGlobal);
-  ModuleScript* GetFetchedModule(nsIURI* aURL, nsIGlobalObject* aGlobal) const;
+  bool IsFetchingModule(ModuleLoadRequest* aRequest) const;
+
+  bool ModuleMapContainsURL(nsIURI* aURL) const;
+  RefPtr<mozilla::GenericNonExclusivePromise> WaitForModuleFetch(nsIURI* aURL);
+  ModuleScript* GetFetchedModule(nsIURI* aURL) const;
 
   friend JSObject* HostResolveImportedModule(
       JSContext* aCx, JS::Handle<JS::Value> aReferencingPrivate,
@@ -758,9 +749,9 @@ class ScriptLoader final : public nsISupports {
   bool mGiveUpEncoding;
 
   // Module map
-  nsRefPtrHashtable<ModuleMapKey, mozilla::GenericNonExclusivePromise::Private>
+  nsRefPtrHashtable<nsURIHashKey, mozilla::GenericNonExclusivePromise::Private>
       mFetchingModules;
-  nsRefPtrHashtable<ModuleMapKey, ModuleScript> mFetchedModules;
+  nsRefPtrHashtable<nsURIHashKey, ModuleScript> mFetchedModules;
 
   nsCOMPtr<nsIConsoleReportCollector> mReporter;
 
diff --git a/dom/script/moz.build b/dom/script/moz.build
index af625e9b93ad..e983a8efdd79 100644
--- a/dom/script/moz.build
+++ b/dom/script/moz.build
@@ -20,7 +20,6 @@ EXPORTS += [
 EXPORTS.mozilla.dom += [
     "AutoEntryScript.h",
     "LoadedScript.h",
-    "ModuleMapKey.h",
     "ScriptDecoding.h",
     "ScriptElement.h",
     "ScriptKind.h",
@@ -33,7 +32,6 @@ UNIFIED_SOURCES += [
     "AutoEntryScript.cpp",
     "LoadedScript.cpp",
     "ModuleLoadRequest.cpp",
-    "ModuleMapKey.cpp",
     "nsIScriptElement.cpp",
     "ScriptElement.cpp",
     "ScriptLoader.cpp",
diff --git a/js/xpconnect/src/Sandbox.cpp b/js/xpconnect/src/Sandbox.cpp
index 2d79a8d8e45e..75964f3a4dc6 100644
--- a/js/xpconnect/src/Sandbox.cpp
+++ b/js/xpconnect/src/Sandbox.cpp
@@ -558,11 +558,6 @@ bool IsSandboxPrototypeProxy(JSObject* obj) {
   return js::IsProxy(obj) && js::GetProxyHandler(obj) == &sandboxProxyHandler;
 }
 
-bool IsWebExtensionContentScriptSandbox(JSObject* obj) {
-  return IsSandbox(obj) &&
-         CompartmentPrivate::Get(obj)->isWebExtensionContentScript;
-}
-
 }  // namespace xpc
 
 // A proxy handler that lets us wrap callables and invoke them with
diff --git a/js/xpconnect/src/xpcpublic.h b/js/xpconnect/src/xpcpublic.h
index dfef8ab06816..91cdd69afea5 100644
--- a/js/xpconnect/src/xpcpublic.h
+++ b/js/xpconnect/src/xpcpublic.h
@@ -138,7 +138,6 @@ bool AllowContentXBLScope(JS::Realm* realm);
 JSObject* NACScope(JSObject* global);
 
 bool IsSandboxPrototypeProxy(JSObject* obj);
-bool IsWebExtensionContentScriptSandbox(JSObject* obj);
 
 // The JSContext argument represents the Realm that's asking the question.  This
 // is needed to properly answer without exposing information unnecessarily
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_contentscript_module_import.js b/toolkit/components/extensions/test/xpcshell/test_ext_contentscript_module_import.js
deleted file mode 100644
index a10715e89198..000000000000
--- a/toolkit/components/extensions/test/xpcshell/test_ext_contentscript_module_import.js
+++ /dev/null
@@ -1,274 +0,0 @@
-"use strict";
-
-const server = createHttpServer({ hosts: ["example.com"] });
-
-server.registerPathHandler("/dummy", (request, response) => {
-  response.setStatusLine(request.httpVersion, 200, "OK");
-  response.setHeader("Content-Type", "text/html", false);
-  response.write("<!DOCTYPE html><html></html>");
-});
-
-server.registerPathHandler("/script.js", (request, response) => {
-  ok(false, "Unexpected request to /script.js");
-});
-
-/* eslint-disable no-unsanitized/method, no-eval, no-implied-eval */
-
-const MODULE1 = `
-  import {foo} from "./module2.js";
-  export let bar = foo;
-
-  let count = 0;
-
-  export function counter () { return count++; }
-`;
-
-const MODULE2 = `export let foo = 2;`;
-
-add_task(async function test_disallowed_import() {
-  let extension = ExtensionTestUtils.loadExtension({
-    manifest: {
-      content_scripts: [
-        {
-          matches: ["http://example.com/dummy"],
-          js: ["main.js"],
-        },
-      ],
-    },
-
-    files: {
-      "main.js": async function() {
-        let disallowedURLs = [
-          "data:text/javascript,void 0",
-          "javascript:void 0",
-          "http://example.com/script.js",
-          URL.createObjectURL(
-            new Blob(["void 0", { type: "text/javascript" }])
-          ),
-        ];
-
-        for (let url of disallowedURLs) {
-          await browser.test.assertRejects(
-            import(url),
-            /error loading dynamically imported module/,
-            `should reject import("${url}")`
-          );
-        }
-
-        browser.test.sendMessage("done");
-      },
-    },
-  });
-
-  await extension.startup();
-  let contentPage = await ExtensionTestUtils.loadContentPage(
-    "http://example.com/dummy"
-  );
-  await extension.awaitMessage("done");
-  await extension.unload();
-  await contentPage.close();
-});
-
-add_task(async function test_normal_import() {
-  let extension = ExtensionTestUtils.loadExtension({
-    manifest: {
-      content_scripts: [
-        {
-          matches: ["http://example.com/dummy"],
-          js: ["main.js"],
-        },
-      ],
-    },
-
-    files: {
-      "main.js": async function() {
-        /* global exportFunction */
-        const url = browser.runtime.getURL("module1.js");
-        let mod = await import(url);
-        browser.test.assertEq(mod.bar, 2);
-
-        browser.test.assertEq(mod.counter(), 0);
-        browser.test.assertEq(mod.counter(), 1);
-
-        await browser.test.assertRejects(
-          window.eval(`import("${url}")`),
-          /error loading dynamically imported module/,
-          "Cannot import script that is not web-accessible from page context"
-        );
-
-        let promise = new Promise((resolve, reject) => {
-          exportFunction(resolve, window, { defineAs: "resolve" });
-          exportFunction(reject, window, { defineAs: "reject" });
-        });
-
-        window.setTimeout(`import("${url}").then(resolve, reject)`, 0);
-
-        await browser.test.assertRejects(
-          promise,
-          /error loading dynamically imported module/,
-          "Cannot import script that is not web-accessible from page context"
-        );
-
-        browser.test.sendMessage("done");
-      },
-      "module1.js": MODULE1,
-      "module2.js": MODULE2,
-    },
-  });
-
-  await extension.startup();
-  let contentPage = await ExtensionTestUtils.loadContentPage(
-    "http://example.com/dummy"
-  );
-
-  await extension.awaitMessage("done");
-
-  // Web page can not import non-web-accessible files.
-  await contentPage.spawn(extension.uuid, async uuid => {
-    let files = ["main.js", "module1.js", "module2.js"];
-
-    for (let file of files) {
-      let url = `moz-extension://${uuid}/${file}`;
-      await Assert.rejects(
-        content.eval(`import("${url}")`),
-        /error loading dynamically imported module/,
-        "Cannot import script that is not web-accessible"
-      );
-    }
-  });
-
-  await extension.unload();
-  await contentPage.close();
-});
-
-add_task(async function test_import_web_accessible() {
-  let extension = ExtensionTestUtils.loadExtension({
-    manifest: {
-      content_scripts: [
-        {
-          matches: ["http://example.com/dummy"],
-          js: ["main.js"],
-        },
-      ],
-      web_accessible_resources: ["module1.js", "module2.js"],
-    },
-
-    files: {
-      "main.js": async function() {
-        let mod = await import(browser.runtime.getURL("module1.js"));
-        browser.test.assertEq(mod.bar, 2);
-        browser.test.assertEq(mod.counter(), 0);
-        browser.test.sendMessage("done");
-      },
-      "module1.js": MODULE1,
-      "module2.js": MODULE2,
-    },
-  });
-
-  await extension.startup();
-  let contentPage = await ExtensionTestUtils.loadContentPage(
-    "http://example.com/dummy"
-  );
-  await extension.awaitMessage("done");
-
-  // Web page can import web-accessible files,
-  // even after WebExtension imported the same files.
-  await contentPage.spawn(extension.uuid, async uuid => {
-    let base = `moz-extension://${uuid}`;
-
-    await Assert.rejects(
-      content.eval(`import("${base}/main.js")`),
-      /error loading dynamically imported module/,
-      "Cannot import script that is not web-accessible"
-    );
-
-    let promise = content.eval(`import("${base}/module1.js")`);
-    let mod = (await promise.wrappedJSObject).wrappedJSObject;
-    Assert.equal(mod.bar, 2, "exported value should match");
-    Assert.equal(mod.counter(), 0, "Counter should be fresh");
-    Assert.equal(mod.counter(), 1, "Counter should be fresh");
-
-    promise = content.eval(`import("${base}/module2.js")`);
-    mod = (await promise.wrappedJSObject).wrappedJSObject;
-    Assert.equal(mod.foo, 2, "exported value should match");
-  });
-
-  await extension.unload();
-  await contentPage.close();
-});
-
-add_task(async function test_import_web_accessible_after_page() {
-  let extension = ExtensionTestUtils.loadExtension({
-    manifest: {
-      content_scripts: [
-        {
-          matches: ["http://example.com/dummy"],
-          js: ["main.js"],
-        },
-      ],
-      web_accessible_resources: ["module1.js", "module2.js"],
-    },
-
-    files: {
-      "main.js": async function() {
-        browser.test.onMessage.addListener(async msg => {
-          browser.test.assertEq(msg, "import");
-
-          const url = browser.runtime.getURL("module1.js");
-          let mod = await import(url);
-          browser.test.assertEq(mod.bar, 2);
-          browser.test.assertEq(mod.counter(), 0, "Counter should be fresh");
-
-          let promise = window.eval(`import("${url}")`);
-          let mod2 = (await promise.wrappedJSObject).wrappedJSObject;
-          browser.test.assertEq(
-            mod2.counter(),
-            2,
-            "Counter should have been incremented by page"
-          );
-
-          browser.test.sendMessage("done");
-        });
-        browser.test.sendMessage("ready");
-      },
-      "module1.js": MODULE1,
-      "module2.js": MODULE2,
-    },
-  });
-
-  await extension.startup();
-  let contentPage = await ExtensionTestUtils.loadContentPage(
-    "http://example.com/dummy"
-  );
-  await extension.awaitMessage("ready");
-
-  // The web page imports the web-accessible files first,
-  // when the WebExtension imports the same file, they should
-  // not be shared.
-  await contentPage.spawn(extension.uuid, async uuid => {
-    let base = `moz-extension://${uuid}`;
-
-    await Assert.rejects(
-      content.eval(`import("${base}/main.js")`),
-      /error loading dynamically imported module/,
-      "Cannot import script that is not web-accessible"
-    );
-
-    let promise = content.eval(`import("${base}/module1.js")`);
-    let mod = (await promise.wrappedJSObject).wrappedJSObject;
-    Assert.equal(mod.bar, 2, "exported value should match");
-    Assert.equal(mod.counter(), 0);
-    Assert.equal(mod.counter(), 1);
-
-    promise = content.eval(`import("${base}/module2.js")`);
-    mod = (await promise.wrappedJSObject).wrappedJSObject;
-    Assert.equal(mod.foo, 2, "exported value should match");
-  });
-
-  extension.sendMessage("import");
-
-  await extension.awaitMessage("done");
-
-  await extension.unload();
-  await contentPage.close();
-});
diff --git a/toolkit/components/extensions/test/xpcshell/xpcshell-common.ini b/toolkit/components/extensions/test/xpcshell/xpcshell-common.ini
index 38d554ac0f05..dd5f20bdfb34 100644
--- a/toolkit/components/extensions/test/xpcshell/xpcshell-common.ini
+++ b/toolkit/components/extensions/test/xpcshell/xpcshell-common.ini
@@ -61,7 +61,6 @@ skip-if = tsan # Bug 1683730
 [test_ext_contentscript_css.js]
 [test_ext_contentscript_exporthelpers.js]
 [test_ext_contentscript_in_background.js]
-[test_ext_contentscript_module_import.js]
 [test_ext_contentscript_restrictSchemes.js]
 [test_ext_contentscript_teardown.js]
 skip-if = tsan # Bug 1683730
diff --git a/xpcom/base/ErrorList.py b/xpcom/base/ErrorList.py
index a7fc17fab94f..e86bb865a069 100755
--- a/xpcom/base/ErrorList.py
+++ b/xpcom/base/ErrorList.py
@@ -789,9 +789,6 @@ with modules["DOM"]:
     # objects being loaded.
     errors["NS_ERROR_RECURSIVE_DOCUMENT_LOAD"] = FAILURE(1038)
 
-    # WebExtension content script may not load this URL.
-    errors["NS_ERROR_DOM_WEBEXT_CONTENT_SCRIPT_URI"] = FAILURE(1039)
-
     # May be used to indicate when e.g. setting a property value didn't
     # actually change the value, like for obj.foo = "bar"; obj.foo = "bar";
     # the second assignment throws NS_SUCCESS_DOM_NO_OPERATION.