Add template parameter to ElementTraversal to iterate over Elements of a specific type

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, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2013 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 655 matching lines @@
     bool isJavaScriptURLAttribute(const Attribute&) const;
 
     RefPtr<ElementData> m_elementData;
 };
 
 DEFINE_NODE_TYPE_CASTS(Element, isElementNode());
 template <typename T> bool isElementOfType(const Element&);
 template <typename T> inline bool isElementOfType(const Node& node) { return node.isElementNode() && isElementOfType<const T>(toElement(node)); }
 template <> inline bool isElementOfType<const Element>(const Element&) { return true; }
 
+// Type casting.
+template<typename T> inline T& toElement(Node& node)
+{
+    ASSERT_WITH_SECURITY_IMPLICATION(isElementOfType<const T>(node));
+    return static_cast<T&>(node);
+}
+template<typename T> inline T* toElement(Node* node)
+{
+    ASSERT_WITH_SECURITY_IMPLICATION(!node || isElementOfType<const T>(*node));
+    return static_cast<T*>(node);
+}
+template<typename T> inline const T& toElement(const Node& node)
+{
+    ASSERT_WITH_SECURITY_IMPLICATION(isElementOfType<const T>(node));
+    return static_cast<const T&>(node);
+}
+template<typename T> inline const T* toElement(const Node* node)
+{
+    ASSERT_WITH_SECURITY_IMPLICATION(!node || isElementOfType<const T>(*node));
+    return static_cast<const T*>(node);
+}
+template<typename T, typename U> inline T* toElement(const RefPtr<U>& node) { return toElement<T>(node.get()); }
+
 inline bool isDisabledFormControl(const Node* node)
 {
     return node->isElementNode() && toElement(node)->isDisabledFormControl();
 }
 
 inline bool Node::hasTagName(const QualifiedName& name) const
 {
     return isElementNode() && toElement(this)->hasTagName(name);
 }
 
@@ skipping 173 matching lines @@
 }
 
 inline bool isShadowHost(const Element* element)
 {
     return element && element->shadow();
 }
 
 } // namespace
 
 #endif