This results in a speed-up of around 30% on all architectures. For local developer builds only. The bots will continue to use level 1 for now.

BUG=
R=yangguo@chromium.org

Review URL: https://codereview.chromium.org/88563002

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@18085 ce2b1a6d-e550-0410-aec6-3dcde31c8c00