Fix sky include guards to match Chromium style

sky/engine/core/dom/DocumentFragment.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2009 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 DocumentFragment_h
-#define DocumentFragment_h
+#ifndef SKY_ENGINE_CORE_DOM_DOCUMENTFRAGMENT_H_
+#define SKY_ENGINE_CORE_DOM_DOCUMENTFRAGMENT_H_
 
 #include "sky/engine/core/dom/ContainerNode.h"
 
 namespace blink {
 
 class DocumentFragment : public ContainerNode {
     DEFINE_WRAPPERTYPEINFO();
 public:
     static PassRefPtr<DocumentFragment> create(Document&);
 
     virtual bool canContainRangeEndPoint() const override final { return true; }
     virtual bool isTemplateContent() const { return false; }
 
 protected:
     DocumentFragment(Document*, ConstructionType = CreateContainer);
     virtual String nodeName() const override final;
 
 private:
     virtual NodeType nodeType() const override final;
     virtual PassRefPtr<Node> cloneNode(bool deep = true) override;
 
     bool isDocumentFragment() const = delete; // This will catch anyone doing an unnecessary check.
 };
 
 DEFINE_NODE_TYPE_CASTS(DocumentFragment, isDocumentFragment());
 
 } // namespace blink
 
-#endif // DocumentFragment_h
+#endif  // SKY_ENGINE_CORE_DOM_DOCUMENTFRAGMENT_H_