Performance and stability improvements on all platforms.

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

Change-Id: I802fec4bfa805740a098c8dd7571775942765235
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1602432
Reviewed-by: v8-ci-autoroll-builder <v8-ci-autoroll-builder@chops-service-accounts.iam.gserviceaccount.com>
Cr-Commit-Position: refs/heads/7.6.134@{#1}
Cr-Branched-From: 47d32fef2baca587d16c256cb7793f7dec0955a1-refs/heads/master@{#61360}