Remove forward declarations from Source/core/dom/custom

Source/core/dom/custom/CustomElementMicrotaskResolutionStep.h

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 48 matching lines @@
 
 #if !defined(NDEBUG)
     virtual void show(unsigned indent) OVERRIDE;
 #endif
 
     RefPtrWillBeMember<CustomElementRegistrationContext> m_context;
     RefPtrWillBeMember<Element> m_element;
     CustomElementDescriptor m_descriptor;
 };
 
-}
+} // namespace blink
 
 #endif // CustomElementMicrotaskResolutionStep_h