This reverts commit 1f0d7d20.

Reason for revert: Speculative revert for roll failures in https://chromium-review.googlesource.com/c/chromium/src/+/3569445

Original change's description:
> cppgc-js: Concurrently process v8::TracedReference
>
> Adds concurrent marking for reaching through v8::TracedReference.
> Before this CL, a v8::TracedReference would always be processed on the
> main thread by pushing a callback for each encountered reference.
>
> This CL now wires up concurrent handling for such references. In particular:
> - Global handles are already marked as well and not repurposed during
>   the same GC cycle.
> - Since global handles are not repurposed, it is enough to
>   double-deref to the V8 object, checking for possible null pointers.
> - The bitmap for global handle flags is mostly non-atomic, with the
>   markbit being the exception.
> - Finally, all state is wired up in CppHeap. Concurrent markers keep
>   their own local worklist while the mutator marker directly pushes to
>   the worklist owned by V8.
>
> Bug: v8:12600
> Change-Id: Ia67dbd18a57dbcccf4dfb9ccfdb9ee438d27fe71
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3516255
> Reviewed-by: Omer Katz <omerkatz@chromium.org>
> Reviewed-by: Dominik Inführ <dinfuehr@chromium.org>
> Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#79736}

Bug: v8:12600
Change-Id: I8a91dcd6880580207bf8d315b264edbe42a794e5
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3568474
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Owners-Override: Leszek Swirski <leszeks@chromium.org>
Reviewed-by: Omer Katz <omerkatz@chromium.org>
Cr-Commit-Position: refs/heads/main@{#79778}