When there is no type feedback yet, ComputeReceiverTypes
should still populate the SmallMapList when the receiver
is a HConstant.

BUG=
R=verwaest@chromium.org

Review URL: https://codereview.chromium.org/230363003

Patch from Petka Antonov <p.antonov@partner.samsung.com>.

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@20646 ce2b1a6d-e550-0410-aec6-3dcde31c8c00