Also turn on deprecation warnings

BUG=v8:3023
R=svenpanne@chromium.org, dcarney@chromium.org
LOG=n

Review URL: https://codereview.chromium.org/83343002

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@18011 ce2b1a6d-e550-0410-aec6-3dcde31c8c00