Fix compilation issue on Mac

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@5468 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/frames.h

@@ -238,7 +238,8 @@ class StackFrame BASE_EMBEDDED {
   friend class StackFrameIterator;
   friend class StackHandlerIterator;
   friend class SafeStackFrameIterator;
-
+  friend class ExitFrameValidator;
+  
  private:
   void operator=(const StackFrame& original);
 };