Replace elementHasLegalLinkAttribute() helper with virtual function

Source/core/html/HTMLImageElement.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2010 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 304 matching lines @@
 
 bool HTMLImageElement::isURLAttribute(const Attribute& attribute) const
 {
     return attribute.name() == srcAttr
         || attribute.name() == lowsrcAttr
         || attribute.name() == longdescAttr
         || (attribute.name() == usemapAttr && attribute.value().string()[0] != '#')
         || HTMLElement::isURLAttribute(attribute);
 }
 
+bool HTMLImageElement::hasLegalLinkAttribute(const QualifiedName& name) const
+{
+    return name == srcAttr || HTMLElement::hasLegalLinkAttribute(name);
+}
+
 const AtomicString& HTMLImageElement::alt() const
 {
     return fastGetAttribute(altAttr);
 }
 
 bool HTMLImageElement::draggable() const
 {
     // Image elements are draggable by default.
     return !equalIgnoringCase(getAttribute(draggableAttr), "false");
 }
@@ skipping 125 matching lines @@
     if (!image)
         return FloatSize();
     LayoutSize size;
     size = image->imageSizeForRenderer(renderer(), 1.0f); // FIXME: Not sure about this.
     if (renderer() && renderer()->isRenderImage() && image->image() && !image->image()->hasRelativeWidth())
         size.scale(toRenderImage(renderer())->imageDevicePixelRatio());
     return size;
 }
 
 }