[turbofan] Use sorted set in JSInliningHeuristic.

[turbofan] Use sorted set in JSInliningHeuristic.

This changes the inlining candidates to be stored in a sorted set of
unique entries instead of a vector. We can avoid the final sorting
operation by amortizing the cost across insertions and also duplicate
entries are not created in the first place. Duplicate entries cause
crashes when candidates are processed.

R=bmeurer@chromium.org
BUG=chromium:549113
LOG=n

Committed: https://crrev.com/2a4336d97ae8d22ba4955c083fa7f6e6f3740e35
Cr-Commit-Position: refs/heads/master@{#31742}

[Benedikt Meurer, 2015-11-03 10:16:51]

LGTM :-)

[Michael Starzinger, 2015-11-03 11:27:07]

The CQ bit was checked by mstarzinger@chromium.org

[Michael Starzinger, 2015-11-03 11:27:07]

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/1430553003/#ps20001
(title: "Fix typo of doom.")

[commit-bot: I haz the power, 2015-11-03 11:27:18]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1430553003/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1430553003/20001

[commit-bot: I haz the power, 2015-11-03 11:29:04]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-11-03 11:29:22]

Patchset 2 (id:??) landed as
https://crrev.com/2a4336d97ae8d22ba4955c083fa7f6e6f3740e35
Cr-Commit-Position: refs/heads/master@{#31742}