Add support for allowing an embedder to get the V8 profile timer event logs.

Contributed by fmeawad@chromium.org

R=yangguo@chromium.org

Review URL: https://codereview.chromium.org/186163002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@19745 ce2b1a6d-e550-0410-aec6-3dcde31c8c00