Bugfix: array constructors that expect a type feedback cell that points
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: https://v8.googlecode.com/svn/branches/bleeding_edge@16693 ce2b1a6d-e550-0410-aec6-3dcde31c8c00