Performance and stability improvements on all platforms.

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

Change-Id: I6db1a80c5f1ee3993240f7d8eee3a2f78a1c04d2
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1614243
Reviewed-by: v8-ci-autoroll-builder <v8-ci-autoroll-builder@chops-service-accounts.iam.gserviceaccount.com>
Cr-Commit-Position: refs/heads/7.6.200@{#1}
Cr-Branched-From: 3cb560adfe26edb586a0e6e655e5a7c4755cad1a-refs/heads/master@{#61573}