Clean up toHTMLFooElement() using DEFINE_NODE_TYPE_CASTS_WITH_FUNCTION

Source/core/html/HTMLTextAreaElement.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2000 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 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 121 matching lines @@
 inline bool isHTMLTextAreaElement(const Node* node)
 {
     return node->hasTagName(HTMLNames::textareaTag);
 }
 
 inline bool isHTMLTextAreaElement(const Element* element)
 {
     return element->hasTagName(HTMLNames::textareaTag);
 }
 
-inline HTMLTextAreaElement* toHTMLTextAreaElement(Node* node)
-{
-    ASSERT_WITH_SECURITY_IMPLICATION(!node || isHTMLTextAreaElement(node));
-    return static_cast<HTMLTextAreaElement*>(node);
-}
+DEFINE_NODE_TYPE_CASTS(HTMLTextAreaElement, hasTagName(HTMLNames::textareaTag));
 
 } //namespace
 
 #endif