Performance and stability improvements on all platforms.

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

Change-Id: I79d73aaf1a2ecb727a0e343198afbdad65f2743e
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1611849
Reviewed-by: v8-ci-autoroll-builder <v8-ci-autoroll-builder@chops-service-accounts.iam.gserviceaccount.com>
Cr-Commit-Position: refs/heads/7.6.185@{#1}
Cr-Branched-From: d9cff61e56e712359cc051dd3ef3f0e3cab1e4f5-refs/heads/master@{#61501}