[turbofan] LiveRange splintering optimizations.

[turbofan] LiveRange splintering optimizations.

Related to 1318893002 - another source of regressions in
benchmarks sensitive to compile time is the splintering
logic. This change addresses some, but not all, of that. In
particular, there are still some places (figuring out if a
range has a hole right where a deferred set of blocks is)
that need another look.

BUG=chromium:524880
LOG=n

Committed: https://crrev.com/2ba2f40c6a331111361585289ecf137ff98b02c7
Cr-Commit-Position: refs/heads/master@{#30425}

[Mircea Trofin, 2015-08-27 01:02:24]

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

[Benedikt Meurer, 2015-08-27 04:40:53]

LGTM once out of bounds crashers are resolved.

[Mircea Trofin, 2015-08-27 18:27:00]

The CQ bit was checked by mtrofin@chromium.org

[Mircea Trofin, 2015-08-27 18:27:00]

The patchset sent to the CQ was uploaded after l-g-t-m from bmeurer@chromium.org
Link to the patchset: https://codereview.chromium.org/1319843002/#ps20001
(title: " ")

[commit-bot: I haz the power, 2015-08-27 18:27:13]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1319843002/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1319843002/20001

[commit-bot: I haz the power, 2015-08-27 18:28:27]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-08-27 18:28:38]

Patchset 2 (id:??) landed as
https://crrev.com/2ba2f40c6a331111361585289ecf137ff98b02c7
Cr-Commit-Position: refs/heads/master@{#30425}