Fix sky include guards to match Chromium style

sky/engine/wtf/dtoa.h

 /*
  *  Copyright (C) 2003, 2008, 2012 Apple Inc. 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.
  *
  *  This library is distributed in the hope that it will be useful,
  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  *  Library General Public License for more details.
  *
  *  You should have received a copy of the GNU Library General Public License
  *  along with this library; see the file COPYING.LIB.  If not, write to
  *  the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  *  Boston, MA 02110-1301, USA.
  *
  */
 
-#ifndef WTF_dtoa_h
-#define WTF_dtoa_h
+#ifndef SKY_ENGINE_WTF_DTOA_H_
+#define SKY_ENGINE_WTF_DTOA_H_
 
 #include "sky/engine/wtf/ASCIICType.h"
 #include "sky/engine/wtf/WTFExport.h"
 #include "sky/engine/wtf/unicode/Unicode.h"
 #include "wtf/dtoa/double-conversion.h"
 
 namespace WTF {
 
 class Mutex;
 
@@ skipping 39 matching lines @@
 
 } // namespace WTF
 
 using WTF::NumberToStringBuffer;
 using WTF::NumberToLStringBuffer;
 using WTF::numberToString;
 using WTF::numberToFixedPrecisionString;
 using WTF::numberToFixedWidthString;
 using WTF::parseDouble;
 
-#endif // WTF_dtoa_h
+#endif  // SKY_ENGINE_WTF_DTOA_H_