now that we are shipping this by default, we can remove the flag.

Change-Id: I298691df3eec934a5add1aa2a2748a0f3a884ab6
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1726452
Commit-Queue: Joshua Litt <joshualitt@chromium.org>
Reviewed-by: Sathya Gunasekaran  <gsathya@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63026}