Storing a map or an immortal immovable object to old space
allocations requires no write barriers if the object is the
new space dominator.

R=hpayer@chromium.org, mstarzinger@chromium.org

Review URL: https://codereview.chromium.org/271103002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@21216 ce2b1a6d-e550-0410-aec6-3dcde31c8c00