Revert "MIPS: Reland r20974: Unify and simplify the FastCloneShallowArrayStub."

Port r21242 (99bd67aa)

Original commit message:
This breaks nosnap.

BUG=
R=plind44@gmail.com

Review URL: https://codereview.chromium.org/271233003

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@21247 ce2b1a6d-e550-0410-aec6-3dcde31c8c00