Remove TreatNullAs=NullString for <frame>, <frameset> and <iframe>

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 184 matching lines @@
     if (Page* page = document().page()) {
         if (received)
             page->focusController().setFocusedFrame(contentFrame());
         else if (page->focusController().focusedFrame() == contentFrame()) // Focus may have already been given to another frame, don't take it away.
             page->focusController().setFocusedFrame(0);
     }
 }
 
 bool HTMLFrameElementBase::isURLAttribute(const Attribute& attribute) const
 {
-    return attribute.name() == srcAttr || HTMLFrameOwnerElement::isURLAttribute(attribute);
+    return attribute.name() == longdescAttr || attribute.name() == srcAttr
+        || HTMLFrameOwnerElement::isURLAttribute(attribute);
 }
 
 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