MIPS: Simplify pending message object handling.

MIPS: Simplify pending message object handling.

Port d4696c484142c601cbd691ae80164043785a3af7

Original commit message:
This moves the decision whether to report a message or not to when
the pending exception is propagated instead of trying to preserve the
decision in a ThreadLocalTop field.

BUG=

Committed: https://crrev.com/811caee0e0acf8bf71dbd8dafb5e5df800784020
Cr-Commit-Position: refs/heads/master@{#27158}

[balazs.kilvady, 2015-03-12 11:02:09]

balazs.kilvady@imgtec.com changed reviewers:
+ akos.palfi@imgtec.com, danno@chromium.org, dusan.milosavljevic@imgtec.com,
gergely.kis@imgtec.com, mstarzinger@chromium.org, paul.lind@imgtec.com

[Michael Starzinger, 2015-03-12 12:01:22]

LGTM.

[balazs.kilvady, 2015-03-12 13:30:49]

The CQ bit was checked by balazs.kilvady@imgtec.com

[commit-bot: I haz the power, 2015-03-12 13:30:58]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1004623002/1

[commit-bot: I haz the power, 2015-03-12 13:54:35]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-03-12 13:54:57]

Patchset 1 (id:??) landed as
https://crrev.com/811caee0e0acf8bf71dbd8dafb5e5df800784020
Cr-Commit-Position: refs/heads/master@{#27158}