Performance and stability improvements on all platforms.

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

Change-Id: I4b4e484bb9708e212585b0c9938395d49c417a0e
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1624725
Reviewed-by: v8-ci-autoroll-builder <v8-ci-autoroll-builder@chops-service-accounts.iam.gserviceaccount.com>
Cr-Commit-Position: refs/heads/7.6.255@{#1}
Cr-Branched-From: 1413e4f53fcfe3371d1a97180265362cecb856aa-refs/heads/master@{#61734}