Fix sky include guards to match Chromium style

sky/engine/core/dom/DocumentSupplementable.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  *           (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) 2013 Google 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 DocumentSupplementable_h
-#define DocumentSupplementable_h
+#ifndef SKY_ENGINE_CORE_DOM_DOCUMENTSUPPLEMENTABLE_H_
+#define SKY_ENGINE_CORE_DOM_DOCUMENTSUPPLEMENTABLE_H_
 
 #include "sky/engine/platform/Supplementable.h"
 
 namespace blink {
 
 class Document;
 
 typedef Supplementable<Document> DocumentSupplementable;
 typedef Supplement<Document> DocumentSupplement;
 
 } // namespace blink
 
-#endif // DocumentSupplementable_h
+#endif  // SKY_ENGINE_CORE_DOM_DOCUMENTSUPPLEMENTABLE_H_