Performance and stability improvements on all platforms.

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

Change-Id: I84906cc4f60306dc6aa1bc2798c5d7c6127dfec8
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1620852
Reviewed-by: v8-ci-autoroll-builder <v8-ci-autoroll-builder@chops-service-accounts.iam.gserviceaccount.com>
Cr-Commit-Position: refs/heads/7.6.223@{#1}
Cr-Branched-From: 5504068f49343e067bc8d9c83f93304605873b63-refs/heads/master@{#61666}