Remove wrong ASSERT on request instance for fallback in DocumentThreadableLoader

Source/core/loader/DocumentThreadableLoader.cpp

 /*
  * Copyright (C) 2011, 2012 Google Inc. All rights reserved.
  * Copyright (C) 2013, Intel Corporation
  *
  * 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.
@@ skipping 401 matching lines @@
         ASSERT(m_fallbackRequestForServiceWorker);
         if (response.wasFallbackRequiredByServiceWorker()) {
             loadFallbackRequestForServiceWorker();
             return;
         }
         m_fallbackRequestForServiceWorker = nullptr;
         m_client->didReceiveResponse(identifier, response, handle);
         return;
     }
 
-    ASSERT(!m_fallbackRequestForServiceWorker);
+    // Here, it's possible that |m_fallbackRequestForServiceWorker| is set.
+    // This means the document was controlled by the ServiceWorker but the
+    // browser process didn't forward the request to the ServiceWorker for
+    // some reason.
+    m_fallbackRequestForServiceWorker = nullptr;
 
     if (!m_sameOriginRequest && m_options.crossOriginRequestPolicy == UseAccessControl) {
         String accessControlErrorDescription;
         if (!passesAccessControlCheck(&m_document, response, effectiveAllowCredentials(), securityOrigin(), accessControlErrorDescription)) {
             reportResponseReceived(identifier, response);
             m_client->didFailAccessControlCheck(ResourceError(errorDomainBlinkInternal, 0, response.url().string(), accessControlErrorDescription));
             return;
         }
     }
 
@@ skipping 188 matching lines @@
         return DoNotAllowStoredCredentials;
     return m_resourceLoaderOptions.allowCredentials;
 }
 
 SecurityOrigin* DocumentThreadableLoader::securityOrigin() const
 {
     return m_securityOrigin ? m_securityOrigin.get() : m_document.securityOrigin();
 }
 
 } // namespace blink