Prepare push to trunk.  Now working on version 3.20.12.

R=ulan@chromium.org

Review URL: https://codereview.chromium.org/21103009

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@15954 ce2b1a6d-e550-0410-aec6-3dcde31c8c00