Fix virtual/override/final usage in Source/core/{fetch,loader,streams,xmlhttprequest}/.

Source/core/loader/DocumentThreadableLoaderClient.h

 /*
  * Copyright (C) 2011 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 24 matching lines @@
 
 namespace blink {
 
 class ResourceRequest;
 class ResourceResponse;
 
 class DocumentThreadableLoaderClient : public ThreadableLoaderClient {
     WTF_MAKE_NONCOPYABLE(DocumentThreadableLoaderClient);
     WTF_MAKE_FAST_ALLOCATED(DocumentThreadableLoaderClient);
 public:
-    bool isDocumentThreadableLoaderClient()  override final { return true; }
+    bool isDocumentThreadableLoaderClient() final { return true; }
 
     virtual void willFollowRedirect(ResourceRequest& /*newRequest*/, const ResourceResponse& /*redirectResponse*/) { }
 
 protected:
     DocumentThreadableLoaderClient() { }
 };
 
 } // namespace blink
 
 #endif // DocumentThreadableLoaderClient_h