Performance and stability improvements on all platforms.

[email protected]

Cq-Include-Trybots: master.tryserver.chromium.linux:linux_chromium_rel_ng
Change-Id: If1859fa7e52c554a1c1df1a3b894fef8af63a0b2
Reviewed-on: https://chromium-review.googlesource.com/887907
Reviewed-by: v8 autoroll <[email protected]>
Cr-Commit-Position: refs/heads/6.6.81@{#1}
Cr-Branched-From: 21532b80c31e45beb5ecf1447c8bb0e86d7921e3-refs/heads/master@{#50877}