[turbofan] Separate JSInliningHeuristic into own class.

[turbofan] Separate JSInliningHeuristic into own class.

This separates the core machinery and the heuristics involved with
inlining functions calls. So far the heuristic only respects our
%SetForceInlineFlag hint, but it will the place where general inlining
heuristics can live without impeding clarity of the core machinery.

R=bmeurer@chromium.org

Committed: https://crrev.com/0a6863f029e5afaf6ea97a9b27087307b8b65b45
Cr-Commit-Position: refs/heads/master@{#31150}

[Benedikt Meurer, 2015-10-07 12:13:57]

LGTM, nice.

[Michael Starzinger, 2015-10-07 12:17:05]

The CQ bit was checked by mstarzinger@chromium.org

[commit-bot: I haz the power, 2015-10-07 12:17:13]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1391903002/40001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1391903002/40001

[commit-bot: I haz the power, 2015-10-07 12:18:25]

Committed patchset #3 (id:40001)

[commit-bot: I haz the power, 2015-10-07 12:18:45]

Patchset 3 (id:??) landed as
https://crrev.com/0a6863f029e5afaf6ea97a9b27087307b8b65b45
Cr-Commit-Position: refs/heads/master@{#31150}