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

Source/modules/websockets/WebSocketChannel.cpp

 /*
  * Copyright (C) 2009, 2012 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 47 matching lines @@
     unsigned lineNumber = 0;
     RefPtr<ScriptCallStack> callStack = createScriptCallStack(1, true);
     if (callStack && callStack->size()) {
         sourceURL = callStack->at(0).sourceURL();
         lineNumber = callStack->at(0).lineNumber();
     }
 
     if (context->isWorkerGlobalScope()) {
         WorkerGlobalScope* workerGlobalScope = toWorkerGlobalScope(context);
         WorkerRunLoop& runLoop = workerGlobalScope->thread()->runLoop();
-        String mode = webSocketChannelMode;
-        mode.append(String::number(runLoop.createUniqueId()));
+        String mode = webSocketChannelMode + String::number(runLoop.createUniqueId());
         return WorkerThreadableWebSocketChannel::create(workerGlobalScope, client, mode, sourceURL, lineNumber);
     }
 
     Document* document = toDocument(context);
     Settings* settings = document->settings();
     if (settings && settings->experimentalWebSocketEnabled()) {
         // FIXME: Create and return an "experimental" WebSocketChannel instead of a MainThreadWebSocketChannel.
         return MainThreadWebSocketChannel::create(document, client, sourceURL, lineNumber);
     }
     return MainThreadWebSocketChannel::create(document, client, sourceURL, lineNumber);
 }
 
 } // namespace WebCore