This reverts commit fee168ce.

Reason for revert: The DCHECK fails when freeing code
(https://ci.chromium.org/ui/p/v8/builders/ci/V8%20Linux64%20GC%20Stress%20-%20custom%20snapshot/38292/overview),
which means that the current code is not correct. The added DCHECK
makes the bots red though, so the state before this CL was still
better.

Original change's description:
> [wasm] Check correctness of thread-local write protection
>
> We make an undocumented assumption in {CodeSpaceWriteScope} that a
> single thread will only work on one module at a time. If this is
> violated, the thread-local {code_space_write_nesting_level_} would
> prevent the second module from being switched to writable.
>
> This CL adds a second thread local (in debug only) to check that if
> there is already a {CodeSpaceWriteScope} open that it contains the same
> {NativeModule} as any nested scope.
>
> R=​jkummerow@chromium.org
>
> Change-Id: I43fa886d9d0fdf0e1846137dc411745fcca471fa
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3074477
> Commit-Queue: Clemens Backes <clemensb@chromium.org>
> Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#76134}

TBR=jkummerow@chromium.org

Change-Id: I5262b0e886f99a64452966345fc084a1ab750459
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3078360Reviewed-by: Clemens Backes <clemensb@chromium.org>
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#76146}