Performance and stability improvements on all platforms.

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

Change-Id: I2300cfc8c4e495eebb21a830b46c74f1d90d1b2b
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1631326
Reviewed-by: v8-ci-autoroll-builder <v8-ci-autoroll-builder@chops-service-accounts.iam.gserviceaccount.com>
Cr-Commit-Position: refs/heads/7.6.289@{#1}
Cr-Branched-From: 19d8bfa5a876b4d40b0bfb0416be847aa966e9b1-refs/heads/master@{#61865}