Replace elementHasLegalLinkAttribute() helper with virtual function

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 159 matching lines @@
     LinkImport* linkImport() const;
     LinkResource* linkResourceToProcess();
 
     void process();
     static void processCallback(Node*);
 
     // From Node and subclassses
     virtual InsertionNotificationRequest insertedInto(ContainerNode*) OVERRIDE;
     virtual void removedFrom(ContainerNode*) OVERRIDE;
     virtual bool isURLAttribute(const Attribute&) const OVERRIDE;
+    virtual bool hasLegalLinkAttribute(const QualifiedName&) const OVERRIDE;
     virtual bool sheetLoaded() OVERRIDE;
     virtual void notifyLoadedSheetAndAllCriticalSubresources(bool errorOccurred) OVERRIDE;
     virtual void startLoadingDynamicSheet() OVERRIDE;
     virtual void finishParsingChildren() OVERRIDE;
 
     // From LinkLoaderClient
     virtual void linkLoaded() OVERRIDE;
     virtual void linkLoadingErrored() OVERRIDE;
     virtual void didStartLinkPrerender() OVERRIDE;
     virtual void didStopLinkPrerender() OVERRIDE;
@@ skipping 12 matching lines @@
     LinkRelAttribute m_relAttribute;
 
     bool m_createdByParser;
     bool m_isInShadowTree;
     int m_beforeLoadRecurseCount;
 };
 
 } //namespace
 
 #endif