Performance and stability improvements on all platforms.

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

Change-Id: Ifbcb7345d90c847dc3792958efdd66c68a64b954
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1582837
Reviewed-by: v8-ci-autoroll-builder <v8-ci-autoroll-builder@chops-service-accounts.iam.gserviceaccount.com>
Cr-Commit-Position: refs/heads/7.6.28@{#1}
Cr-Branched-From: 0c879d1cd05446fbbc0993a791c62bd6937beb86-refs/heads/master@{#60997}