Performance and stability improvements on all platforms.

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

Change-Id: Idf8fa1be5c5efabb8764eb76a4ecceadd0a5afdd
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1600415
Reviewed-by: v8-ci-autoroll-builder <v8-ci-autoroll-builder@chops-service-accounts.iam.gserviceaccount.com>
Cr-Commit-Position: refs/heads/7.6.116@{#1}
Cr-Branched-From: 3bfb0a235bbd2606b6af29478659d6c391d58e3c-refs/heads/master@{#61308}