MIPS: Remove code object from StackHandler.

MIPS: Remove code object from StackHandler.

Port e0aa8ebf933b4c659e1c4a01ba244c5de452ff1c

Original commit message:
This reduces the size of the StackHandler by one word. We no longer
need to keep track of the code object, as the stack walk finds it.

BUG=

Committed: https://crrev.com/fd012f1080eb8fccdefe64ff854abf2852943d56
Cr-Commit-Position: refs/heads/master@{#27120}

[balazs.kilvady, 2015-03-10 17:27:01]

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, 2015-03-10 17:44:27]

LGTM.

[balazs.kilvady, 2015-03-10 18:08:04]

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

[commit-bot: I haz the power, 2015-03-10 18:08:25]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/990903008/1

[paul.l..., 2015-03-10 18:10:03]

Also LGTM ....

[commit-bot: I haz the power, 2015-03-10 19:07:21]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-03-10 19:07:33]

Patchset 1 (id:??) landed as
https://crrev.com/fd012f1080eb8fccdefe64ff854abf2852943d56
Cr-Commit-Position: refs/heads/master@{#27120}