The bootstrapper accidentally overwrote the constructor property of the Object
prototype because it used initial_object_prototype() as prototype for WeakMap.
Unfortunately this is not possible for experimental natives because they are
installed after the snapshot initialization finished.

R=erik.corry@gmail.com
TEST=mjsunit/mirror-object,mjsunit/harmony/weakmaps

Review URL: http://codereview.chromium.org/7624041

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@9067 ce2b1a6d-e550-0410-aec6-3dcde31c8c00