This is a reland of c88994f8

Turned out to not be the issue.

Original change's description:
> Fix Array.prototype.sort speed regression
>
> CanUseSameAccessor<ElementsAccessor: type> is array-sort.tq is super
> performance-critical. Reverting the type-safe cleanup made in this
> function while landing Array.prototype.slice.
>
> Bug=chromium:852764
>
> Change-Id: I1252d2ff8e431581f916794807e59abb39248abb
> Reviewed-on: https://chromium-review.googlesource.com/c/1317815
> Reviewed-by: Jakob Gruber <jgruber@chromium.org>
> Commit-Queue: Daniel Clifford <danno@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#57248}

TBR=danno@chromium.org

Change-Id: I627a131a8525ae4e131c6467561cab9832f3792f
Reviewed-on: https://chromium-review.googlesource.com/c/1319581Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Cr-Commit-Position: refs/heads/master@{#57270}