Make TreeScope::baseURL pure virtual

Source/core/dom/TreeScope.h

 /*
  * Copyright (C) 2011 Google Inc. All Rights Reserved.
  * Copyright (C) 2012 Apple Inc. All Rights Reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 108 matching lines @@
         }
     }
 
     void removedLastRefToScope();
 
     bool isInclusiveAncestorOf(const TreeScope&) const;
     unsigned short comparePosition(const TreeScope&) const;
 
     Element* getElementByAccessKey(const String& key) const;
 
-    const KURL& baseURL() const { return m_baseURL; }
+    const KURL& baseURL() const;
     KURL completeURL(const String&) const;
 
 protected:
     TreeScope(ContainerNode*, Document*);
     TreeScope(Document*);
     virtual ~TreeScope();
 
     void destroyTreeScopeData();
     void setDocument(Document& document) { m_document = &document; }
     void setParentTreeScope(TreeScope&);
@@ skipping 51 matching lines @@
 inline bool operator!=(const TreeScope& a, const TreeScope& b) { return !(a == b); }
 inline bool operator!=(const TreeScope& a, const TreeScope* b) { return !(a == b); }
 inline bool operator!=(const TreeScope* a, const TreeScope& b) { return !(a == b); }
 
 RenderObject* rendererFromPoint(Document*, int x, int y, LayoutPoint* localPoint = 0);
 TreeScope* commonTreeScope(Node*, Node*);
 
 } // namespace WebCore
 
 #endif // TreeScope_h