[turbofan] Re-wire greedy.

[turbofan] Re-wire greedy.

We completely un-wired the greedy allocator to focus on the
stackchecks in loops (splintering) work. This change re-wires greedy,
still behind its flag. For now, enabling the greedy allocator disables
the stackchecks in loops feature (and range splintering), so that we are
at the baseline we left it at.

The main contribution in this change is adapting the codebase after
the live range model refactoring, whereby RegisterAllocationData's
live_ranges() contains just top-level ranges, and children are accessed
via their parents.

BUG=

Committed: https://crrev.com/71779375adb4a4de86f5f02ba0103769f92b376c
Cr-Commit-Position: refs/heads/master@{#30492}

[Mircea Trofin, 2015-08-31 13:48:29]

Patchset #1 (id:1) has been deleted

[Mircea Trofin, 2015-08-31 14:12:15]

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

[Benedikt Meurer, 2015-08-31 19:19:52]

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

[Benedikt Meurer, 2015-08-31 19:19:52]

LGTM from my side.

[Mircea Trofin, 2015-08-31 19:31:30]

The CQ bit was checked by mtrofin@chromium.org

[commit-bot: I haz the power, 2015-08-31 19:31:37]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1320363002/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1320363002/20001

[commit-bot: I haz the power, 2015-08-31 19:31:38]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-08-31 19:31:39]

All required reviewers (with asterisk prefixes) have not yet approved this CL.

No L-G-T-M from a valid reviewer yet. Only full committers are accepted.
Even if an L-G-T-M may have been provided, it was from a non-committer,
_not_ a full super star committer.
See http://www.chromium.org/getting-involved/become-a-committer
Note that this has nothing to do with OWNERS files.

[Jarin, 2015-09-01 04:01:11]

lgtm

[Mircea Trofin, 2015-09-01 04:40:23]

The CQ bit was checked by mtrofin@chromium.org

[commit-bot: I haz the power, 2015-09-01 04:40:27]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1320363002/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1320363002/20001

[commit-bot: I haz the power, 2015-09-01 04:42:41]

Committed patchset #1 (id:20001)

[commit-bot: I haz the power, 2015-09-01 04:42:50]

Patchset 1 (id:??) landed as
https://crrev.com/71779375adb4a4de86f5f02ba0103769f92b376c
Cr-Commit-Position: refs/heads/master@{#30492}