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

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

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

TEST=cctest,mjsunit,unittests

Committed: https://crrev.com/d211608a3eb7ef3da4d04fd4f5a8540dedbd1faa
Cr-Commit-Position: refs/heads/master@{#25814}

[Benedikt Meurer, 2014-12-15 10:26:08]

bmeurer@chromium.org changed reviewers:
+ svenpanne@chromium.org

[Benedikt Meurer, 2014-12-15 10:26:08]

PTAL

[Sven Panne, 2014-12-15 10:45:29]

lgtm

[Sven Panne, 2014-12-15 10:45:34]

The CQ bit was checked by svenpanne@chromium.org

[commit-bot: I haz the power, 2014-12-15 10:46:08]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/801333002/20001

[commit-bot: I haz the power, 2014-12-15 11:14:10]

Committed patchset #2 (id:20001)

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

Patchset 2 (id:??) landed as
https://crrev.com/d211608a3eb7ef3da4d04fd4f5a8540dedbd1faa
Cr-Commit-Position: refs/heads/master@{#25814}