Use DEFINE_NODE_TYPE_CASTS instead of using manual toHTMLFooElement()

Source/core/html/HTMLMapElement.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2004, 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 36 matching lines @@
     HTMLMapElement(const QualifiedName&, Document&);
 
     virtual void parseAttribute(const QualifiedName&, const AtomicString&) OVERRIDE;
 
     virtual InsertionNotificationRequest insertedInto(ContainerNode*) OVERRIDE;
     virtual void removedFrom(ContainerNode*) OVERRIDE;
 
     AtomicString m_name;
 };
 
-inline HTMLMapElement* toHTMLMapElement(Node* node)
-{
-    ASSERT_WITH_SECURITY_IMPLICATION(!node || node->hasTagName(HTMLNames::mapTag));
-    return static_cast<HTMLMapElement*>(node);
-}
+DEFINE_NODE_TYPE_CASTS(HTMLMapElement, hasTagName(HTMLNames::mapTag));
 
 } //namespace
 
 #endif