MIPS: Array constructor expects AllocationSite or undefined as feedback.

Port r20064 (d2ccdc6)

Original commit message:
Redefine Array constructor to expect an AllocationSite in the feedback
register or undefined. This will make code simpler as we support
pretenuring feedback for all constructed objects.

BUG=
R=plind44@gmail.com

Review URL: https://codereview.chromium.org/204613002

Patch from Balazs Kilvady <kilvadyb@homejinni.com>.

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@20086 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Fix polymorphic keyed loads for SLOPPY_ARGUMENTS_ELEMENTS

BUG=chromium:350867
LOG=y
R=verwaest@chromium.org

Review URL: https://codereview.chromium.org/203303010

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@20087 ce2b1a6d-e550-0410-aec6-3dcde31c8c00