Performance and stability improvements on all platforms.

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

Change-Id: I36e805d38adb540254112bb65f8a62d70d20c99d
Reviewed-on: https://chromium-review.googlesource.com/c/1495900
Reviewed-by: v8-ci-autoroll-builder <v8-ci-autoroll-builder@chops-service-accounts.iam.gserviceaccount.com>
Cr-Commit-Position: refs/heads/7.4.257@{#1}
Cr-Branched-From: 6141741064875a24aab111077aa7af394c05ebd1-refs/heads/master@{#59956}