This reverts commit 9981f2e5.

Reason for revert: This CL landed by accident, we decided back then to land a different CL.

Original change's description:
> [d8] quit() should not dispose the isolate
>
> R=​cbruni@chromium.org
>
> Bug: chromium:1338150
> Change-Id: I5e5f8ede942dd37112766812a3c84a356f0b6ca9
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3714355
> Reviewed-by: Camillo Bruni <cbruni@chromium.org>
> Commit-Queue: Andreas Haas <ahaas@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#81827}

Bug: chromium:1338150
Change-Id: Ib058d90a0c09e7cc65bdecee20580dd9e1f184d9
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3773776
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Reviewed-by: Clemens Backes <clemensb@chromium.org>
Auto-Submit: Andreas Haas <ahaas@chromium.org>
Cr-Commit-Position: refs/heads/main@{#81838}