Share optimized code for closures.

src/frames.h

Index: src/frames.h
===================================================================
--- src/frames.h	(revision 11527)
+++ src/frames.h	(working copy)
@@ -572,6 +572,8 @@
   inline explicit OptimizedFrame(StackFrameIterator* iterator);
 
  private:
+  JSFunction* LiteralAt(FixedArray* literal_array, int literal_id);
+
   friend class StackFrameIterator;
 };