Performance and stability improvements on all platforms.

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

Change-Id: I5265df6465356582ba6cba7a8ab41ba4a4c1915e
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1619101
Reviewed-by: v8-ci-autoroll-builder <v8-ci-autoroll-builder@chops-service-accounts.iam.gserviceaccount.com>
Cr-Commit-Position: refs/heads/7.6.221@{#1}
Cr-Branched-From: 76f851995337ed943fd07967e3330bd97094eca5-refs/heads/master@{#61662}