Performance and stability improvements on all platforms.

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

Change-Id: I8d7c6d06daa18dc31ab2e33dfd2b2c5cbe822a05
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1633771
Reviewed-by: v8-ci-autoroll-builder <v8-ci-autoroll-builder@chops-service-accounts.iam.gserviceaccount.com>
Cr-Commit-Position: refs/heads/7.6.306@{#1}
Cr-Branched-From: bb2c7bd3301dc032d42a26c396323983735011e4-refs/heads/master@{#61906}