Introduce DEFINE_ELEMENT_DATA_TYPE_CASTS, and use it

Source/core/dom/Element.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Peter Kelly (pmk@post.com)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2003-2011, 2013, 2014 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
@@ skipping 768 matching lines @@
 
 inline bool Element::hasClass() const
 {
     return elementData() && elementData()->hasClass();
 }
 
 inline UniqueElementData& Element::ensureUniqueElementData()
 {
     if (!elementData() || !elementData()->isUnique())
         createUniqueElementData();
-    return static_cast<UniqueElementData&>(*m_elementData);
+    return toUniqueElementData(*m_elementData);
 }
 
 // Put here to make them inline.
 inline bool Node::hasID() const
 {
     return isElementNode() && toElement(this)->hasID();
 }
 
 inline bool Node::hasClass() const
 {
@@ skipping 72 matching lines @@
     static PassRefPtrWillBeRawPtr<T> create(const QualifiedName&, Document&)
 #define DEFINE_ELEMENT_FACTORY_WITH_TAGNAME(T) \
     PassRefPtrWillBeRawPtr<T> T::create(const QualifiedName& tagName, Document& document) \
     { \
         return adoptRefWillBeNoop(new T(tagName, document)); \
     }
 
 } // namespace
 
 #endif