Sync XHR on Worker should not crash when response arrives immediately

third_party/WebKit/Source/core/loader/WorkerThreadableLoader.cpp

 /*
  * Copyright (C) 2009, 2010 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 428 matching lines @@
         forwarder = new AsyncTaskForwarder(loaderProxy);
 
     MainThreadLoaderHolder* mainThreadLoaderHolder = new MainThreadLoaderHolder(forwarder, workerThreadLifecycleContext);
     if (mainThreadLoaderHolder->wasContextDestroyedBeforeObserverCreation()) {
         // The thread is already terminating.
         forwarder->abort();
         mainThreadLoaderHolder->m_forwarder = nullptr;
         return;
     }
     mainThreadLoaderHolder->m_workerLoader = workerLoader;
+    forwarder->forwardTask(BLINK_FROM_HERE, createCrossThreadTask(&WorkerThreadableLoader::didStart, wrapCrossThreadPersistent(workerLoader), wrapCrossThreadPersistent(mainThreadLoaderHolder)));
     mainThreadLoaderHolder->start(*toDocument(executionContext), std::move(request), options, resourceLoaderOptions);
-    forwarder->forwardTask(BLINK_FROM_HERE, createCrossThreadTask(&WorkerThreadableLoader::didStart, wrapCrossThreadPersistent(workerLoader), wrapCrossThreadPersistent(mainThreadLoaderHolder)));
 }
 
 WorkerThreadableLoader::MainThreadLoaderHolder::~MainThreadLoaderHolder()
 {
     DCHECK(isMainThread());
     DCHECK(!m_workerLoader);
 }
 
 void WorkerThreadableLoader::MainThreadLoaderHolder::overrideTimeout(unsigned long timeoutMilliseconds)
 {
@@ skipping 138 matching lines @@
     const ResourceLoaderOptions& originalResourceLoaderOptions)
 {
     DCHECK(isMainThread());
     ResourceLoaderOptions resourceLoaderOptions = originalResourceLoaderOptions;
     resourceLoaderOptions.requestInitiatorContext = WorkerContext;
     m_mainThreadLoader = DocumentThreadableLoader::create(document, this, options, resourceLoaderOptions);
     m_mainThreadLoader->start(ResourceRequest(request.get()));
 }
 
 } // namespace blink