Replace elementHasLegalLinkAttribute() helper with virtual function

Source/core/html/HTMLAnchorElement.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) 2007, 2008, 2009, 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 79 matching lines @@
     virtual void parseAttribute(const QualifiedName&, const AtomicString&) OVERRIDE;
 
 private:
     virtual bool supportsFocus() const OVERRIDE;
     virtual bool isMouseFocusable() const OVERRIDE;
     virtual bool isKeyboardFocusable() const OVERRIDE;
     virtual void defaultEventHandler(Event*) OVERRIDE FINAL;
     virtual void setActive(bool = true) OVERRIDE FINAL;
     virtual void accessKeyAction(bool sendMouseEvents) OVERRIDE FINAL;
     virtual bool isURLAttribute(const Attribute&) const OVERRIDE FINAL;
+    virtual bool hasLegalLinkAttribute(const QualifiedName&) const OVERRIDE FINAL;
     virtual bool canStartSelection() const OVERRIDE FINAL;
     virtual short tabIndex() const OVERRIDE FINAL;
     virtual bool draggable() const OVERRIDE FINAL;
     virtual bool isInteractiveContent() const OVERRIDE FINAL;
 
     void sendPings(const KURL& destinationURL);
     AtomicString target() const;
     void handleClick(Event*);
 
     enum EventType {
@@ skipping 26 matching lines @@
 }
 
 // Functions shared with the other anchor elements (i.e., SVG).
 
 bool isEnterKeyKeydownEvent(Event*);
 bool isLinkClick(Event*);
 
 } // namespace WebCore
 
 #endif // HTMLAnchorElement_h