[Turbofan] Re-enable single splinter.

[Turbofan] Re-enable single splinter.

Revert "Revert of [turbofan] Splinter into one range.
(patchset #2 id:80001 of https://codereview.chromium.org/1391023007/ )"

This reverts commit 23a8837fcc8a212a4a2608a9bf53f908a7a91728.

Also added a CHECK in Merge to validate that splitting yields a different
range and thus advances the algorithm. Ran stress bots successfully. Likely my earlier change in Splintering addressed the stress test scenario
that was looping infinitely.

BUG=

Committed: https://crrev.com/3e2e2062e783dd76dac21313013585da5a4605be
Cr-Commit-Position: refs/heads/master@{#31430}

[Mircea Trofin, 2015-10-20 22:26:44]

Description was changed from

==========
[Turbofan] Re-enable single splinter.


Revert "Revert of [turbofan] Splinter into one range.
(patchset #2 id:80001 of https://codereview.chromium.org/1391023007/ )"

This reverts commit 23a8837fcc8a212a4a2608a9bf53f908a7a91728.

BUG=
==========

to

==========
[Turbofan] Re-enable single splinter.


Revert "Revert of [turbofan] Splinter into one range.
(patchset #2 id:80001 of https://codereview.chromium.org/1391023007/ )"

This reverts commit 23a8837fcc8a212a4a2608a9bf53f908a7a91728.

Also added a CHECK in Merge to validate that splitting yields a different 
range and thus advances the algorithm. Ran stress bots successfully. Likely my
earlier change in Splintering addressed the stress test scenario 
that was looping infinitely.

BUG=
==========

[Mircea Trofin, 2015-10-20 22:26:44]

mtrofin@chromium.org changed reviewers:
+ bmeurer@chromium.org, jarin@chromium.org

[Benedikt Meurer, 2015-10-21 03:50:57]

bmeurer@chromium.org changed required reviewers:
+ jarin@chromium.org

[Benedikt Meurer, 2015-10-21 03:50:58]

Please try with re-enabling the single Merge exit in
JSNativeContextSpecialization.

[Mircea Trofin, 2015-10-21 04:46:05]

On 2015/10/21 03:50:58, Benedikt Meurer wrote:
> Please try with re-enabling the single Merge exit in
> JSNativeContextSpecialization.

Done, ran tests locally, (--exhaustive-variants), they pass.

[Benedikt Meurer, 2015-10-21 08:07:54]

bmeurer@chromium.org changed required reviewers:
- jarin@chromium.org

[Benedikt Meurer, 2015-10-21 08:07:54]

LGTM.

[Benedikt Meurer, 2015-10-21 08:08:02]

The CQ bit was checked by bmeurer@chromium.org

[commit-bot: I haz the power, 2015-10-21 08:08:13]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1406983004/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1406983004/20001

[commit-bot: I haz the power, 2015-10-21 08:09:36]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-10-21 08:09:48]

Patchset 2 (id:??) landed as
https://crrev.com/3e2e2062e783dd76dac21313013585da5a4605be
Cr-Commit-Position: refs/heads/master@{#31430}