Remove duplicated headers from the testing/ directory

Source/testing/runner/MockWebRTCPeerConnectionHandler.cpp

 /*
  * Copyright (C) 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 21 matching lines @@
 
 #include "MockConstraints.h"
 #include "MockWebRTCDTMFSenderHandler.h"
 #include "MockWebRTCDataChannelHandler.h"
 #include "TestInterfaces.h"
 #include "public/platform/WebMediaConstraints.h"
 #include "public/platform/WebMediaStream.h"
 #include "public/platform/WebMediaStreamTrack.h"
 #include "public/platform/WebRTCDataChannelInit.h"
 #include "public/platform/WebRTCPeerConnectionHandlerClient.h"
-#include "public/platform/WebRTCSessionDescription.h"
-#include "public/platform/WebRTCSessionDescriptionRequest.h"
-#include "public/platform/WebRTCStatsRequest.h"
 #include "public/platform/WebRTCStatsResponse.h"
 #include "public/platform/WebRTCVoidRequest.h"
 #include "public/platform/WebString.h"
 #include "public/platform/WebVector.h"
 #include "public/testing/WebTestDelegate.h"
 
 using namespace blink;
 
 namespace WebTestRunner {
 
@@ skipping 247 matching lines @@
 {
     return new MockWebRTCDTMFSenderHandler(track, m_interfaces->delegate());
 }
 
 void MockWebRTCPeerConnectionHandler::stop()
 {
     m_stopped = true;
 }
 
 }