This reverts commit f16d3abf.

Reason for revert: register_count() is read from the heap on the
background thread. This is only safe when FLAG_local_heaps is enabled
(set to true) but this isn't the case on tip-of-tree.

Original change's description:
> [compiler] Access the heap for BytecodeArray int/Register members
>
> We can create a new macro to skip the xxxData classes and read directly
> from the heap.
>
> Bug: v8:7790
> Change-Id: I8de9ba0aee78c74d4c3113eb6bc4870a314de552
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2362687
> Commit-Queue: Santiago Aboy Solanes <solanes@chromium.org>
> Reviewed-by: Georg Neis <neis@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#69471}

TBR=neis@chromium.org,solanes@chromium.org

Bug: v8:7790
Change-Id: I35bdd44721ce1e9d2f46df7cf5d1f413e22d9acf
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2372602Reviewed-by: Dominik Inführ <dinfuehr@chromium.org>
Reviewed-by: Nico Hartmann <nicohartmann@chromium.org>
Reviewed-by: Santiago Aboy Solanes <solanes@chromium.org>
Commit-Queue: Dominik Inführ <dinfuehr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69547}