Performance and stability improvements on all platforms.

TBR=v8-ci-autoroll-builder@chops-service-accounts.iam.gserviceaccount.com

Change-Id: Ic177c4a2d723a8e5be5b615342167347f0439b37
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1610240
Reviewed-by: v8-ci-autoroll-builder <v8-ci-autoroll-builder@chops-service-accounts.iam.gserviceaccount.com>
Cr-Commit-Position: refs/heads/7.6.165@{#1}
Cr-Branched-From: 210856603f3125bfd0c6d4370dd6e3a7a3946a84-refs/heads/master@{#61446}