Use DEFINE_NODE_TYPE_CASTS instead of using manual toHTMLFooElement()

Source/core/html/HTMLDataListElement.h

 /*
  * Copyright (c) 2009, Google Inc. All rights reserved.
  * Copyright (C) 2010 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
@@ skipping 31 matching lines @@
     static PassRefPtr<HTMLDataListElement> create(const QualifiedName&, Document&);
 
     PassRefPtr<HTMLCollection> options();
 
     void optionElementChildrenChanged();
 
 private:
     HTMLDataListElement(const QualifiedName&, Document&);
 };
 
-inline HTMLDataListElement* toHTMLDataListElement(Node* node)
-{
-    ASSERT_WITH_SECURITY_IMPLICATION(!node || node->hasTagName(HTMLNames::datalistTag));
-    return static_cast<HTMLDataListElement*>(node);
-}
+DEFINE_NODE_TYPE_CASTS(HTMLDataListElement, hasTagName(HTMLNames::datalistTag));
 
 } // namespace WebCore
 
 #endif // HTMLDataListElement_h