MIPS: Clean up the global object naming madness.

Port r22117 (e9244d6)

BUG=
R=palfia@homejinni.com

Review URL: https://codereview.chromium.org/364863002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@22170 ce2b1a6d-e550-0410-aec6-3dcde31c8c00