Fix sky include guards to match Chromium style

sky/engine/core/css/StyleSheet.h

 /*
  * (C) 1999-2003 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2004, 2006, 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 StyleSheet_h
-#define StyleSheet_h
+#ifndef SKY_ENGINE_CORE_CSS_STYLESHEET_H_
+#define SKY_ENGINE_CORE_CSS_STYLESHEET_H_
 
 #include "sky/engine/bindings/core/v8/ScriptWrappable.h"
 #include "sky/engine/core/css/parser/CSSParserMode.h"
 #include "sky/engine/platform/heap/Handle.h"
 #include "sky/engine/wtf/Forward.h"
 #include "sky/engine/wtf/RefCounted.h"
 
 namespace blink {
 
 class CSSRule;
@@ skipping 14 matching lines @@
     virtual MediaList* media() const { return 0; }
     virtual String type() const = 0;
 
     virtual void clearOwnerNode() = 0;
     virtual KURL baseURL() const = 0;
     virtual bool isCSSStyleSheet() const { return false; }
 };
 
 } // namespace blink
 
-#endif
+#endif  // SKY_ENGINE_CORE_CSS_STYLESHEET_H_