MIPS: Fix for StringCharCodeAtGenerator for vector-ics.

MIPS: Fix for StringCharCodeAtGenerator for vector-ics.

Register pop order bug only surfaced after vector-ic optimization
in https://codereview.chromium.org/1053843003 was landed.

TEST=mjsunit/string-index.js
BUG=

Committed: https://crrev.com/e8fe70492102377a0aed8b18f760f839d00d52c9
Cr-Commit-Position: refs/heads/master@{#27894}

[paul.l..., 2015-04-16 02:28:34]

paul.lind@imgtec.com changed reviewers:
+ akos.palfi@imgtec.com, balazs.kilvady@imgtec.com,
dusan.milosavljevic@imgtec.com, mvstanton@chromium.org

[paul.l..., 2015-04-16 02:28:35]

PTAL.

[mvstanton, 2015-04-16 06:29:32]

Awesome to find this!
LGTM.

[paul.l..., 2015-04-16 15:33:19]

The CQ bit was checked by paul.lind@imgtec.com

[commit-bot: I haz the power, 2015-04-16 15:33:27]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1074123004/1

[commit-bot: I haz the power, 2015-04-16 16:07:01]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-04-16 16:07:15]

Patchset 1 (id:??) landed as
https://crrev.com/e8fe70492102377a0aed8b18f760f839d00d52c9
Cr-Commit-Position: refs/heads/master@{#27894}