Set USE(NEW_THEME) in config.h instead of a gyp file

Source/config.h

 /*
  * Copyright (C) 2004, 2005, 2006, 2013 Apple Inc.
  * Copyright (C) 2009 Google Inc. All rights reserved.
  * Copyright (C) 2007-2009 Torch Mobile, Inc.
  * Copyright (C) 2010, 2011 Research In Motion Limited. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
@@ skipping 118 matching lines @@
 
 #if !OS(WIN) && !OS(ANDROID)
 #define HAVE_TM_GMTOFF 1
 #define HAVE_TM_ZONE 1
 #define HAVE_TIMEGM 1
 #endif
 
 #if OS(MACOSX)
 #define HAVE_DISPATCH_H 1
 #define HAVE_PTHREAD_SETNAME_NP 1
+#define WTF_USE_NEW_THEME 1
 #endif /* OS(MACOSX) */
 
 #if OS(WIN)
 
 // If we don't define these, they get defined in windef.h.
 // We want to use std::min and std::max.
 #ifndef max
 #define max max
 #endif
 #ifndef min
@@ skipping 20 matching lines @@
 #define SKIP_STATIC_CONSTRUCTORS_ON_GCC 1
 #endif
 
 #ifndef __STDC_FORMAT_MACROS
 #define __STDC_FORMAT_MACROS 1
 #endif
 
 #if OS(LINUX) || OS(ANDROID)
 #define WTF_USE_HARFBUZZ 1
 #endif