Patch by Peter Varga.

BUG=v8:1336
TEST=cctest/test-api/CallAsFunction

Review URL: http://codereview.chromium.org/6883045

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@7781 ce2b1a6d-e550-0410-aec6-3dcde31c8c00