Switch speech synthesis from compile-flag to runtime-flag.

Source/modules/speech/DOMWindowSpeechSynthesis.h

 /*
  * Copyright (C) 2013 Apple 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:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
  *
  * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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 #ifndef DOMWindowSpeechSynthesis_h
 #define DOMWindowSpeechSynthesis_h
 
-#if ENABLE(SPEECH_SYNTHESIS)
-
 #include "core/page/DOMWindowProperty.h"
 #include "core/platform/Supplementable.h"
 #include "modules/speech/SpeechSynthesis.h"
 
 namespace WebCore {
     
 class DOMWindow;
 
 class DOMWindowSpeechSynthesis : public Supplement<DOMWindow>, public DOMWindowProperty {
 public:
     virtual ~DOMWindowSpeechSynthesis();
     
     static SpeechSynthesis* speechSynthesis(DOMWindow*);
     static DOMWindowSpeechSynthesis* from(DOMWindow*);
     
 private:
     explicit DOMWindowSpeechSynthesis(DOMWindow*);
     
     SpeechSynthesis* speechSynthesis();
     static const char* supplementName();
     
     RefPtr<SpeechSynthesis> m_speechSynthesis;
 };
 
 } // namespace WebCore
 
-#endif // ENABLE(SPEECH_SYNTHESIS)
-
 #endif // DOMWindowSpeechSynthesis_h