Performance and stability improvements on all platforms.

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

Change-Id: I2c5ebbf9f2a1622da2dc01e4431d5115cc750eea
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1596000
Reviewed-by: v8-ci-autoroll-builder <v8-ci-autoroll-builder@chops-service-accounts.iam.gserviceaccount.com>
Cr-Commit-Position: refs/heads/7.6.101@{#1}
Cr-Branched-From: 7d17fd465db8ab1014d721ef85de0d4eef8334d4-refs/heads/master@{#61229}