Performance and stability improvements on all platforms.

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

Change-Id: I59d6c1741e1761b0eba9d5f8324b9156d2149a60
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1588732
Reviewed-by: v8-ci-autoroll-builder <v8-ci-autoroll-builder@chops-service-accounts.iam.gserviceaccount.com>
Cr-Commit-Position: refs/heads/7.6.70@{#1}
Cr-Branched-From: 150a8abaf594b4a1995d74f287b193f94a59bb9a-refs/heads/master@{#61105}