Stores to old space allocations require no write barriers if the
object is the new space dominator and the value is not in new space.

R=hpayer@chromium.org

Review URL: https://codereview.chromium.org/290173003

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@21360 ce2b1a6d-e550-0410-aec6-3dcde31c8c00