Replace elementHasLegalLinkAttribute() helper with virtual function

Source/core/html/HTMLFrameElementBase.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2000 Simon Hausmann (hausmann@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@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
@@ skipping 186 matching lines @@
             page->focusController().setFocusedFrame(nullptr);
     }
 }
 
 bool HTMLFrameElementBase::isURLAttribute(const Attribute& attribute) const
 {
     return attribute.name() == longdescAttr || attribute.name() == srcAttr
         || HTMLFrameOwnerElement::isURLAttribute(attribute);
 }
 
+bool HTMLFrameElementBase::hasLegalLinkAttribute(const QualifiedName& name) const
+{
+    return name == hrefAttr || HTMLFrameOwnerElement::hasLegalLinkAttribute(name);
+}
+
 bool HTMLFrameElementBase::isHTMLContentAttribute(const Attribute& attribute) const
 {
     return attribute.name() == srcdocAttr || HTMLFrameOwnerElement::isHTMLContentAttribute(attribute);
 }
 
 int HTMLFrameElementBase::width()
 {
     document().updateLayoutIgnorePendingStylesheets();
     if (!renderBox())
         return 0;
     return renderBox()->width();
 }
 
 int HTMLFrameElementBase::height()
 {
     document().updateLayoutIgnorePendingStylesheets();
     if (!renderBox())
         return 0;
     return renderBox()->height();
 }
 
 } // namespace WebCore