MIPS: [turbofan] Remove the no-context hack for JSToNumber.

MIPS: [turbofan] Remove the no-context hack for JSToNumber.

Port d211608a3eb7ef3da4d04fd4f5a8540dedbd1faa

Original commit message:
The ToNumberStub is now able to handle all plain primitives (Numbers,
Booleans, Null, Undefined and Strings) without context access.

TEST=cctest,mjsunit,unittests
BUG=

Committed: https://crrev.com/9167c996d3496fa3ea087c1de555d4a9dfa7c515
Cr-Commit-Position: refs/heads/master@{#25824}

[balazs.kilvady, 2014-12-15 13:26:45]

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

[dusmil.imgtec, 2014-12-15 14:24:23]

LGTM

[balazs.kilvady, 2014-12-15 15:31:17]

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

[commit-bot: I haz the power, 2014-12-15 15:31:46]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/803973002/1

[commit-bot: I haz the power, 2014-12-15 16:01:57]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2014-12-17 10:13:36]

Patchset 1 (id:??) landed as
https://crrev.com/9167c996d3496fa3ea087c1de555d4a9dfa7c515
Cr-Commit-Position: refs/heads/master@{#25824}