Performance and stability improvements on all platforms.

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

Change-Id: I4579bf7c00b6ec143b962b7e314cb1d1afe4fed5
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1584220
Reviewed-by: v8-ci-autoroll-builder <v8-ci-autoroll-builder@chops-service-accounts.iam.gserviceaccount.com>
Cr-Commit-Position: refs/heads/7.6.35@{#1}
Cr-Branched-From: bb1b538abf9a9e288065354933aff2a982204146-refs/heads/master@{#61012}