Performance and stability improvements on all platforms.

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

Change-Id: I8f71f80297ad81dd6bfd970b0c6d5a46d294f380
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1595782
Reviewed-by: v8-ci-autoroll-builder <v8-ci-autoroll-builder@chops-service-accounts.iam.gserviceaccount.com>
Cr-Commit-Position: refs/heads/7.6.98@{#1}
Cr-Branched-From: 5782a628581fd917242e8f9c5aa5dda7fda0ed89-refs/heads/master@{#61225}