Introduce toHTMLLinkElement

Source/core/html/HTMLLinkElement.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2003, 2008, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2011 Google 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 185 matching lines @@
     String m_type;
     String m_media;
     RefPtr<DOMSettableTokenList> m_sizes;
     LinkRelAttribute m_relAttribute;
 
     bool m_createdByParser;
     bool m_isInShadowTree;
     int m_beforeLoadRecurseCount;
 };
 
+inline HTMLLinkElement* toHTMLLinkElement(Node* node)
+{
+    ASSERT_WITH_SECURITY_IMPLICATION(!node || node->hasTagName(HTMLNames::linkTag));
+    return static_cast<HTMLLinkElement*>(node);
+}
+
 } //namespace
 
 #endif