Keyed stores to super with numeric keys.

R=verwaest@chromium.org, arv@chromium.org, ishell@chromium.org
BUG=v8:3330
LOG=N

Review URL: https://codereview.chromium.org/649603003

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@24696 ce2b1a6d-e550-0410-aec6-3dcde31c8c00