Performance and stability improvements on all platforms.

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

Change-Id: I822d079795f6fe65f94499cdaea76fb9fc5c194e
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1594422
Reviewed-by: v8-ci-autoroll-builder <v8-ci-autoroll-builder@chops-service-accounts.iam.gserviceaccount.com>
Cr-Commit-Position: refs/heads/7.6.90@{#1}
Cr-Branched-From: 6d0078e4f803a7347fca88019f94f75dec2cd6b9-refs/heads/master@{#61196}