to an AllocationSite were being passed the undefined object in some
cases. Clearly separate the cases where we have an AllocationSite and
where we don't in the general ArrayConstructorStub.

BUG=
R=mstarzinger@chromium.org

Review URL: https://codereview.chromium.org/23477071

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@16693 ce2b1a6d-e550-0410-aec6-3dcde31c8c00