Fix sky include guards to match Chromium style

sky/engine/core/css/CSSStyleSheet.h

 /*
  * (C) 1999-2003 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2004, 2006, 2007, 2008, 2009, 2010, 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 CSSStyleSheet_h
-#define CSSStyleSheet_h
+#ifndef SKY_ENGINE_CORE_CSS_CSSSTYLESHEET_H_
+#define SKY_ENGINE_CORE_CSS_CSSSTYLESHEET_H_
 
 #include "sky/engine/core/css/CSSRule.h"
 #include "sky/engine/core/css/StyleSheet.h"
 #include "sky/engine/platform/heap/Handle.h"
 #include "sky/engine/wtf/Noncopyable.h"
 #include "sky/engine/wtf/text/TextPosition.h"
 
 namespace blink {
 
 class BisonCSSParser;
@@ skipping 106 matching lines @@
 inline CSSStyleSheet::RuleMutationScope::~RuleMutationScope()
 {
     if (m_styleSheet)
         m_styleSheet->didMutateRules();
 }
 
 DEFINE_TYPE_CASTS(CSSStyleSheet, StyleSheet, sheet, sheet->isCSSStyleSheet(), sheet.isCSSStyleSheet());
 
 } // namespace blink
 
-#endif
+#endif  // SKY_ENGINE_CORE_CSS_CSSSTYLESHEET_H_