Remove unnecessary includes from dom.

third_party/WebKit/Source/core/dom/custom/CustomElement.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 17 matching lines @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #ifndef CustomElement_h
 #define CustomElement_h
 
 #include "core/CoreExport.h"
 #include "core/dom/custom/CustomElementDefinition.h"
 #include "wtf/Allocator.h"
 #include "wtf/HashMap.h"
-#include "wtf/Noncopyable.h"
-#include "wtf/PassRefPtr.h"
-#include "wtf/RefPtr.h"
 #include "wtf/Vector.h"
 #include "wtf/text/AtomicString.h"
 
 namespace blink {
 
 class CustomElementMicrotaskImportStep;
 class Document;
 class HTMLImportChild;
 
 class CORE_EXPORT CustomElement {
@@ skipping 21 matching lines @@
     static void didDetach(Element*, const Document&);
     static void wasDestroyed(Element*);
 
 private:
     static Vector<AtomicString>& embedderCustomElementNames();
 };
 
 } // namespace blink
 
 #endif // CustomElement_h