expression stack when it is already there.  Also, cleanup up the
(two!) extra copies of the arguments object left on the stack.
Review URL: http://codereview.chromium.org/5667

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@410 ce2b1a6d-e550-0410-aec6-3dcde31c8c00