Introduce isHTMLHtmlElement and toHTMLHtmlElement

Source/core/html/HTMLHtmlElement.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2000 Simon Hausmann <hausmann@kde.org>
  * Copyright (C) 2004, 2006, 2010 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
  * version 2 of the License, or (at your option) any later version.
@@ skipping 23 matching lines @@
     static PassRefPtr<HTMLHtmlElement> create(const QualifiedName&, Document*);
 
     void insertedByParser();
 
 private:
     HTMLHtmlElement(const QualifiedName&, Document*);
 
     virtual bool isURLAttribute(const Attribute&) const OVERRIDE;
 };
 
+inline bool isHTMLHtmlElement(const Node* node)
+{
+    return node->hasTagName(HTMLNames::htmlTag);
+}
+
+inline bool isHTMLHtmlElement(const Element* element)
+{
+    return element->hasTagName(HTMLNames::htmlTag);
+}
+
+inline HTMLHtmlElement* toHTMLHtmlElement(Node* node)
+{
+    ASSERT_WITH_SECURITY_IMPLICATION(!node || isHTMLHtmlElement(node));
+    return static_cast<HTMLHtmlElement*>(node);
+}
+
 } // namespace
 
 #endif