If --debug-code is on, check that returned value and Top::has_pending_exception
agree on exception state.

Review URL: http://codereview.chromium.org/6450004

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@6692 ce2b1a6d-e550-0410-aec6-3dcde31c8c00