This is a reland of 8f1c985c

Original change's description:
> [heap] Reduce page size to 256KB
> 
> The page size of PPC is kept unchanged because PPC has larger
> physical pages (64KB).
> 
> Bug: chromium:852420
> 
> Change-Id: Ib888ea00a476ff103e00211dbb439186148ef81e
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1481631
> Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
> Reviewed-by: Hannes Payer <hpayer@chromium.org>
> Reviewed-by: Junliang Yan <jyan@ca.ibm.com>
> Cr-Commit-Position: refs/heads/master@{#60296}

Bug: chromium:852420
Change-Id: Id0fbe4759f6fa750bc00100ca521453317dff9ff
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1529006
Auto-Submit: Ulan Degenbaev <ulan@chromium.org>
Reviewed-by: Hannes Payer <hpayer@chromium.org>
Commit-Queue: Hannes Payer <hpayer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#60329}