This reverts commit 90b39673.

Reason for revert: These functions are in use by d8-js.cc

Original change's description:
> [cleanup] Remove three unused proxy runtime functions
>
> R=​jgruber@chromium.org
>
> Bug: v8:9183
> Change-Id: I789295e5bbea682b2e46ccf5a55c69dc74f0ed72
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1617669
> Auto-Submit: Simon Zünd <szuend@chromium.org>
> Commit-Queue: Jakob Gruber <jgruber@chromium.org>
> Reviewed-by: Jakob Gruber <jgruber@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#61632}

TBR=jgruber@chromium.org,szuend@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: v8:9183, v8:10289
Change-Id: Ibd8566151f036efe73c869dcfd2cfee2a559489b
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2083299Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Reviewed-by: Georg Neis <neis@chromium.org>
Commit-Queue: Toon Verwaest <verwaest@chromium.org>
Cr-Commit-Position: refs/heads/master@{#66536}