This is a reland of 1d837093

Original change's description:
> [heap] Clean-up MemoryChunk allocation area constants.
> 
> Change-Id: I8ba59546ab93c7af98bc5ece2f0160628844dd92
> Reviewed-on: https://chromium-review.googlesource.com/c/1280584
> Reviewed-by: Yang Guo <yangguo@chromium.org>
> Commit-Queue: Hannes Payer <hpayer@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#56908}

Change-Id: I110b70ee5cb5609e54e24e17f183b8c6d6086b8a
Reviewed-on: https://chromium-review.googlesource.com/c/1297318Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Commit-Queue: Hannes Payer <hpayer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#56941}