This reverts commit 1fb26d83.

Reason for revert: Flushes out TSan issues: https://ci.chromium.org/p/v8/builders/ci/V8%20Linux64%20TSAN/25782

Original change's description:
> [regalloc] Enable control flow aware allocation
> 
> This is a test to see how much and where we regress. We have seen
> some quirks of our current allocator that do not show up in this
> new approach, so we need to decide whether to stabilize the new
> allocation scheme. Performance numbers are a key indicator for that
> decision.
> 
> This patch is intended to be reverted after stability and performance
> numbers are in (i.e. after a few days).
> 
> Change-Id: I8df8ff7de8efa82a8abbdfa1d21d7877756f129e
> Bug: v8:9088
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1552786
> Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
> Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
> Commit-Queue: Sigurd Schneider <sigurds@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#60643}

TBR=mstarzinger@chromium.org,jarin@chromium.org,sigurds@chromium.org

Change-Id: Ia1934b01b0909479b2bd52ba686cc9b3fb364b4b
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: v8:9088
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1554682Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#60645}