http://wiki.ecmascript.org/doku.php?id=harmony:specification_drafts, section
15.14.5.3 and 15.14.5.2

BUG=v8:2400

Review URL: https://codereview.chromium.org/11409002
Patch from Erik Arvidsson <arv@chromium.org>.

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@12909 ce2b1a6d-e550-0410-aec6-3dcde31c8c00