MIPS: Fixing performance regression in issue 1787.
MIPS: Fixing performance regression in issue 1787.

Port r9812 (c1644a9d)

Note: MIPS already had the fix for this regression.
This commit only adds the extra assertions.

BUG=
TEST=

Review URL: http://codereview.chromium.org/8343030
Patch from Gergely Kis <gergely@homejinni.com>.

git-svn-id: b158db1e4b4ab85d4c9e510fdef4b1e8c614b15b@9827 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

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