[turbofan] Make native context specialization dependent on the typed pipeline.

[turbofan] Make native context specialization dependent on the typed pipeline.

Also refactor the JSGlobalSpecialization somewhat to reduce the amount
of duplicated code somewhat.

R=jarin@chromium.org
BUG=v8:4470
LOG=n

Committed: https://crrev.com/ffd0a2ae74187af5668c43ea45ef66c2d7cd2444
Cr-Commit-Position: refs/heads/master@{#31286}

[Benedikt Meurer, 2015-10-15 09:17:29]

Hey Jaro,

Please take a look.

Thanks,
Benedikt

[Jarin, 2015-10-15 09:43:54]

lgtm

[Benedikt Meurer, 2015-10-15 10:24:35]

The CQ bit was checked by bmeurer@chromium.org

[commit-bot: I haz the power, 2015-10-15 10:24:41]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1403223003/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1403223003/1

[commit-bot: I haz the power, 2015-10-15 10:25:45]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-10-15 10:25:53]

Patchset 1 (id:??) landed as
https://crrev.com/ffd0a2ae74187af5668c43ea45ef66c2d7cd2444
Cr-Commit-Position: refs/heads/master@{#31286}