R=rossberg@chromium.org
BUG=v8:2355
TEST=mjsunit/harmony/generators-objects

Review URL: https://codereview.chromium.org/13956023

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@14366 ce2b1a6d-e550-0410-aec6-3dcde31c8c00