The checks are split out from "extra checks" which are too expensive to
turn on by default.

R=danno@chromium.org

Review URL: https://codereview.chromium.org/18316006

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@15548 ce2b1a6d-e550-0410-aec6-3dcde31c8c00