This enum defined three modes of doing inlining:
kGeneralInlining, kRestrictedInlining, kStressInlining.
kStressInlining was unused. kRestrictedInlining meant
that JSInliningHeuristic::Reduce would return NoChange,
but only after wasting some time inspecting calls. This
is now replaced by simply not installing JSInliningHeuristic
as a reducer when inlining is disabled.

Note: There is still a --stress-inline flag, which sets
(through flag implications) a bunch of parameters that affect
inlining.

Change-Id: I05bafbe3f1f35610d7035a2c71c5ac17bdb80758
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1936473
Auto-Submit: Georg Neis <neis@chromium.org>
Reviewed-by: Mythri Alle <mythria@chromium.org>
Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Commit-Queue: Tobias Tebbi <tebbi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65196}