Port r15002 (d2f0fac)

Original commit message:
Add full-codegen support for the ES6 for-of iteration statement.

TEST=mjsunit/harmony/iteration-semantics
BUG=v8:2214
R=plind44@gmail.com

Review URL: https://codereview.chromium.org/15995040

Patch from Balazs Kilvady <kilvadyb@homejinni.com>.

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@15015 ce2b1a6d-e550-0410-aec6-3dcde31c8c00