This is a reland of 6798619a

Original change's description:
> [d8] Add d8 global variable
>
> - Add a a "d8" global variable where d8 can provide helpers.
>   This in in preparation of adding d8.log for testing our log parsers
>   written in JavaScript.
>
> - Separate d8 helper creation into individual functions.
>
> Bug: v8:10668
> Change-Id: I84e434452463afb93ae403f890d8841b20b00703
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2400990
> Reviewed-by: Toon Verwaest <verwaest@chromium.org>
> Commit-Queue: Camillo Bruni <cbruni@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#69801}


Tbr: verwaest@chromium.org
Bug: v8:10668
Change-Id: If3256ec4e11f01ef1dc5c2e61fa33ed6d7a6aee3
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2409274Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Commit-Queue: Camillo Bruni <cbruni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69867}