MIPS: Refactor RegExpStub to check lazily.
MIPS: Refactor RegExpStub to check lazily.

Port r13727 (55a760ec)

BUG=

Review URL: https://codereview.chromium.org/12374073

git-svn-id: b158db1e4b4ab85d4c9e510fdef4b1e8c614b15b@13798 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

UniversalFuture/moosh,UniversalFuture/moosh,UniversalFuture/moosh,UniversalFuture/moosh