Make FrameTree::uniqueName() more unique.

Source/core/page/FrameTree.h

 /*
  * Copyright (C) 2006 Apple Computer, Inc.
  *
  * 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.
  *
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 43 matching lines @@
         unsigned childCount() const;
 
         LocalFrame* scopedChild(unsigned index) const;
         LocalFrame* scopedChild(const AtomicString& name) const;
         unsigned scopedChildCount() const;
         void invalidateScopedChildCount();
 
     private:
         LocalFrame* deepLastChild() const;
         AtomicString uniqueChildName(const AtomicString& requestedName) const;
+        bool uniqueNameExists(const AtomicString& name) const;
         unsigned scopedChildCount(TreeScope*) const;
 
         LocalFrame* m_thisFrame;
 
         AtomicString m_name; // The actual frame name (may be empty).
         AtomicString m_uniqueName;
 
         mutable unsigned m_scopedChildCount;
     };
 
 } // namespace WebCore
 
 #ifndef NDEBUG
 // Outside the WebCore namespace for ease of invocation from gdb.
 void showFrameTree(const WebCore::LocalFrame*);
 #endif
 
 #endif // FrameTree_h