Replace elementHasLegalLinkAttribute() helper with virtual function

Source/core/html/HTMLAppletElement.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2004, 2006, 2008, 2009 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 23 matching lines @@
     static PassRefPtr<HTMLAppletElement> create(Document&, bool createdByParser);
 
 protected:
     virtual RenderWidget* renderWidgetForJSBindings() const OVERRIDE;
 
 private:
     HTMLAppletElement(Document&, bool createdByParser);
 
     virtual void parseAttribute(const QualifiedName&, const AtomicString&) OVERRIDE;
     virtual bool isURLAttribute(const Attribute&) const OVERRIDE;
+    virtual bool hasLegalLinkAttribute(const QualifiedName&) const OVERRIDE;
 
     virtual bool rendererIsNeeded(const RenderStyle&) OVERRIDE;
     virtual RenderObject* createRenderer(RenderStyle*) OVERRIDE;
 
     virtual RenderWidget* existingRenderWidget() const OVERRIDE;
     virtual void updateWidgetInternal() OVERRIDE;
 
     bool canEmbedJava() const;
     bool canEmbedURL(const KURL&) const;
 
     virtual bool shouldRegisterAsNamedItem() const OVERRIDE { return true; }
     virtual bool shouldRegisterAsExtraNamedItem() const OVERRIDE { return true; }
 };
 
 }
 
 #endif