commit for zhangk@codeaurora.org.  See
http://codereview.chromium.org/568029 and
http://codereview.chromium.org/2019003

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@4618 ce2b1a6d-e550-0410-aec6-3dcde31c8c00