Performance and stability improvements on all platforms.

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

Change-Id: Iff2122f2740074419cc1404635a9067ac840372d
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1630538
Reviewed-by: v8-ci-autoroll-builder <v8-ci-autoroll-builder@chops-service-accounts.iam.gserviceaccount.com>
Cr-Commit-Position: refs/heads/7.6.281@{#1}
Cr-Branched-From: 6cc1fffc51c607c93f1fc09dcf2eba296beebbe0-refs/heads/master@{#61852}