Remove unnecessary includes from dom.

third_party/WebKit/Source/core/dom/custom/CustomElementRegistrationContext.cpp

 /*
  * 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 23 matching lines @@
 #include "core/HTMLNames.h"
 #include "core/SVGNames.h"
 #include "core/dom/Document.h"
 #include "core/dom/Element.h"
 #include "core/dom/custom/CustomElement.h"
 #include "core/dom/custom/CustomElementDefinition.h"
 #include "core/dom/custom/CustomElementScheduler.h"
 #include "core/html/HTMLElement.h"
 #include "core/html/HTMLUnknownElement.h"
 #include "core/svg/SVGUnknownElement.h"
-#include "wtf/RefPtr.h"
 
 namespace blink {
 
 CustomElementRegistrationContext::CustomElementRegistrationContext()
     : m_candidates(CustomElementUpgradeCandidateMap::create())
 {
 }
 
 void CustomElementRegistrationContext::registerElement(Document* document, CustomElementConstructorBuilder* constructorBuilder, const AtomicString& type, CustomElement::NameSet validNames, ExceptionState& exceptionState)
 {
@@ skipping 99 matching lines @@
     context->didGiveTypeExtension(element, element->document().convertLocalName(type));
 }
 
 DEFINE_TRACE(CustomElementRegistrationContext)
 {
     visitor->trace(m_candidates);
     visitor->trace(m_registry);
 }
 
 } // namespace blink