Remove 'String::append' from some of the blink source.

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 50 matching lines @@
 WorkerThreadableLoader::~WorkerThreadableLoader()
 {
     m_bridge.destroy();
 }
 
 void WorkerThreadableLoader::loadResourceSynchronously(WorkerGlobalScope* workerGlobalScope, const ResourceRequest& request, ThreadableLoaderClient& client, const ThreadableLoaderOptions& options)
 {
     WorkerRunLoop& runLoop = workerGlobalScope->thread()->runLoop();
 
     // Create a unique mode just for this synchronous resource load.
-    String mode = loadResourceSynchronouslyMode;
-    mode.append(String::number(runLoop.createUniqueId()));
+    String mode = loadResourceSynchronouslyMode + String::number(runLoop.createUniqueId());
 
     RefPtr<WorkerThreadableLoader> loader = WorkerThreadableLoader::create(workerGlobalScope, &client, mode, request, options);
     MessageQueueWaitResult result = MessageQueueMessageReceived;
     while (!loader->done() && result != MessageQueueTerminated)
         result = runLoop.runInMode(workerGlobalScope, mode);
 
     if (!loader->done() && result == MessageQueueTerminated)
         loader->cancel();
 }
 
@@ skipping 179 matching lines @@
     ASSERT_UNUSED(context, context->isWorkerGlobalScope());
     workerClientWrapper->didFailRedirectCheck();
 }
 
 void WorkerThreadableLoader::MainThreadBridge::didFailRedirectCheck()
 {
     m_loaderProxy.postTaskForModeToWorkerGlobalScope(createCallbackTask(&workerGlobalScopeDidFailRedirectCheck, m_workerClientWrapper), m_taskMode);
 }
 
 } // namespace WebCore