Prepare push to trunk.  Now working on version 3.18.4.

R=yangguo@chromium.org

Review URL: https://chromiumcodereview.appspot.com/14139031

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@14403 ce2b1a6d-e550-0410-aec6-3dcde31c8c00