Performance and stability improvements on all platforms.

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

Change-Id: Ic1794bc6888370842665c090d3ff554992ab5ed5
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1601818
Reviewed-by: v8-ci-autoroll-builder <v8-ci-autoroll-builder@chops-service-accounts.iam.gserviceaccount.com>
Cr-Commit-Position: refs/heads/7.6.130@{#1}
Cr-Branched-From: 6e4026038170d514e9a2c42e37eeb589981bd90e-refs/heads/master@{#61354}