This reverts commit a850668c.

Reason for revert: new test flaking on many bots, e.g. https://ci.chromium.org/ui/p/v8/builders/ci/V8%20Win32/31068/overview

Original change's description:
> [d8] Fix a crash when getting the worker's onmessage handler
>
> Bug: chromium:1162473
> Change-Id: Ided2f52882aaf02e1dc9a8d0ba883fedf029464d
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2663004
> Reviewed-by: Camillo Bruni <cbruni@chromium.org>
> Commit-Queue: Marja Hölttä <marja@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#72473}

TBR=marja@chromium.org,cbruni@chromium.org

Change-Id: I5ec056185967974a94fd61baec8a75e855e1a272
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: chromium:1162473, v8:11383
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2666693Reviewed-by: Clemens Backes <clemensb@chromium.org>
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#72481}