Bug 1662435 - Assert request is not already in another list before appending to bytecode cache queue. r=smaug

Add a safety check before appending a request to the bytecode cache queue to see if it already exists in another list.

Differential Revision: https://phabricator.services.mozilla.com/D88984

dom/script/ScriptLoader.cpp

@@ -3034,6 +3034,7 @@ LoadedScript* ScriptLoader::GetActiveScript(JSContext* aCx) {
 void ScriptLoader::RegisterForBytecodeEncoding(ScriptLoadRequest* aRequest) {
   MOZ_ASSERT(aRequest->mCacheInfo);
   MOZ_ASSERT(aRequest->mScript);
+  MOZ_DIAGNOSTIC_ASSERT(!aRequest->isInList());
   mBytecodeEncodingQueue.AppendElement(aRequest);
 }