[ServiceWorker] Fix ResourceFetcher::isControlledByServiceWorker to support HTMLImports.

Source/core/fetch/ResourceLoader.cpp

 /*
  * Copyright (C) 2006, 2007, 2010, 2011 Apple Inc. All rights reserved.
  *           (C) 2007 Graham Dennis (graham.dennis@gmail.com)
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
@@ skipping 344 matching lines @@
     bool isValidStateTransition = (m_connectionState == ConnectionStateStarted || m_connectionState == ConnectionStateReceivedResponse);
     // In the case of multipart loads, calls to didReceiveData & didReceiveResponse can be interleaved.
     RELEASE_ASSERT(isMultipartPayload || isValidStateTransition);
     m_connectionState = ConnectionStateReceivedResponse;
 
     const ResourceResponse& resourceResponse = response.toResourceResponse();
 
     if (responseNeedsAccessControlCheck()) {
         if (response.wasFetchedViaServiceWorker()) {
             if (response.wasFallbackRequiredByServiceWorker()) {
+                ASSERT(m_fallbackRequestForServiceWorker);
                 m_loader->cancel();
                 m_loader.clear();
                 m_connectionState = ConnectionStateStarted;
                 m_request = *m_fallbackRequestForServiceWorker;
                 m_loader = adoptPtr(blink::Platform::current()->createURLLoader());
                 ASSERT(m_loader);
                 blink::WrappedResourceRequest wrappedRequest(m_request);
                 m_loader->loadAsynchronously(wrappedRequest, this);
                 return;
             }
@@ skipping 180 matching lines @@
     m_requestCountTracker.clear();
 }
 
 ResourceRequest& ResourceLoader::applyOptions(ResourceRequest& request) const
 {
     request.setAllowStoredCredentials(m_options.allowCredentials == AllowStoredCredentials);
     return request;
 }
 
 }