MIPS: Enable pretenuring of fast literals in high promotion mode.

Port r14248 (144e215a)

BUG=

Review URL: https://codereview.chromium.org/13903005

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@14256 ce2b1a6d-e550-0410-aec6-3dcde31c8c00