Relanding r14006 and r14009 that were reverted in r14031

TBR=danno
BUG=None

Review URL: https://codereview.chromium.org/13460002

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@14108 ce2b1a6d-e550-0410-aec6-3dcde31c8c00