Revert "Unify and fix checkers for duplicate object literal properties."

This reverts commit 12c68518bd2c74dc4e44d928c84c17f98ca63359.
(r17114)

R=mstarzinger@chromium.org
TBR=mstarzinger@chromium.org

Review URL: https://codereview.chromium.org/26732006

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@17122 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Ensure only whitelisted stubs have sse2 versions in the snapshot.

BUG=
R=mvstanton@chromium.org

Review URL: https://codereview.chromium.org/26680002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@17123 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Simplify redundant phi elimination and use during canonicalization too.

BUG=
R=verwaest@chromium.org

Review URL: https://codereview.chromium.org/25896006

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@17124 ce2b1a6d-e550-0410-aec6-3dcde31c8c00