[turbofan] Correctify JSToBoolean lowering.

[turbofan] Correctify JSToBoolean lowering.

Introduce a new AnyToBoolean simplified operator to handle the later
lowering of boolean conversions. Previously we tried to hack that with
the generic JSToBoolean, having its context set to zero, but that lead
to various problems/bugs and did not handle all cases.

TEST=cctest,unittests
R=jarin@chromium.org

Committed: https://crrev.com/9def087efcd844342c35f42628bac4ead49cac81
Cr-Commit-Position: refs/heads/master@{#25958}

[Benedikt Meurer, 2015-01-02 14:18:49]

PTAL

[Jarin, 2015-01-05 09:31:52]

lgtm

[Benedikt Meurer, 2015-01-05 13:28:12]

The CQ bit was checked by bmeurer@chromium.org

[commit-bot: I haz the power, 2015-01-05 13:28:34]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/800833003/60001

[Benedikt Meurer, 2015-01-05 13:43:42]

The CQ bit was unchecked by bmeurer@chromium.org

[Benedikt Meurer, 2015-01-05 13:44:39]

Committed patchset #4 (id:60001) manually as
9def087efcd844342c35f42628bac4ead49cac81 (presubmit successful).

[commit-bot: I haz the power, 2015-01-05 13:44:40]

Patchset 4 (id:??) landed as
https://crrev.com/9def087efcd844342c35f42628bac4ead49cac81
Cr-Commit-Position: refs/heads/master@{#25958}