Performance and stability improvements on all platforms.

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

Change-Id: I16cedd74a872abf0b6bf885fa4e68022094887e1
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1610203
Reviewed-by: v8-ci-autoroll-builder <v8-ci-autoroll-builder@chops-service-accounts.iam.gserviceaccount.com>
Cr-Commit-Position: refs/heads/7.6.179@{#1}
Cr-Branched-From: f6f31d154eeaf77f03754373be333bbd1b5a5043-refs/heads/master@{#61490}