Bug 1958495: Add CancelFetchingModules for BETA. a=RyanVM

Apply the fix in https://phabricator.services.mozilla.com/D257677 to
BETA.

Original Revision: https://phabricator.services.mozilla.com/D260293

Differential Revision: https://phabricator.services.mozilla.com/D260572

dom/script/ScriptLoader.cpp

@@ -1816,6 +1816,7 @@ void ScriptLoader::CancelAndClearScriptLoadRequests() {
   mOffThreadCompilingRequests.CancelRequestsAndClear();
 
   if (mModuleLoader) {
+    mModuleLoader->CancelFetchingModules();
     mModuleLoader->CancelAndClearDynamicImports();
   }
 

js/loader/ModuleLoaderBase.cpp

@@ -683,7 +683,7 @@ nsresult ModuleLoaderBase::OnFetchComplete(ModuleLoadRequest* aRequest,
   MOZ_ASSERT(NS_SUCCEEDED(rv) == bool(aRequest->mModuleScript));
   SetModuleFetchFinishedAndResumeWaitingRequests(aRequest, rv);
 
-  if (!aRequest->IsErrored()) {
+  if (!aRequest->IsErrored() && !aRequest->IsCanceled()) {
     StartFetchingModuleDependencies(aRequest);
   }
 
@@ -1180,6 +1180,20 @@ ModuleLoaderBase::~ModuleLoaderBase() {
   LOG(("ModuleLoaderBase::~ModuleLoaderBase %p", this));
 }
 
+void ModuleLoaderBase::CancelFetchingModules() {
+  for (const auto& entry : mFetchingModules) {
+    RefPtr<LoadingRequest> loadingRequest = entry.GetData();
+    loadingRequest->mRequest->Cancel();
+
+    for (const auto& request : loadingRequest->mWaiting) {
+      request->Cancel();
+    }
+  }
+
+  // We don't clear mFetchingModules here, as the fetching requests might arrive
+  // after the global is still shutting down.
+}
+
 void ModuleLoaderBase::Shutdown() {
   CancelAndClearDynamicImports();
 

js/loader/ModuleLoaderBase.h

@@ -290,6 +290,8 @@ class ModuleLoaderBase : public nsISupports {
   explicit ModuleLoaderBase(ScriptLoaderInterface* aLoader,
                             nsIGlobalObject* aGlobalObject);
 
+  void CancelFetchingModules();
+
   // Called to break cycles during shutdown to prevent memory leaks.
   void Shutdown();