Properly blacklist ES6 for-of statement for TurboFan.

R=bmeurer@chromium.org
TEST=mjsunit/es6

Review URL: https://codereview.chromium.org/547343002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@23769 ce2b1a6d-e550-0410-aec6-3dcde31c8c00