This reverts commit 9b0d5cb1.

Reason for revert: Seems to fail on gc-stress bots (e.g. https://ci.chromium.org/ui/p/v8/builders/ci/V8%20Linux64%20GC%20Stress%20-%20custom%20snapshot/43472/overview)

Original change's description:
> [ext-code-space] Fix Code vs non-Code comparisons
>
> When external code space is enabled comparing Code and non-Code objects
> by looking at compressed values is not always correct. Such an approach
> works only for comparing Code vs Code objects or non-Code vs non-Code
> objects.
>
> This CL instroduces SLOW_DCHECK into Object comparison operators to
> ensure that such a comparison is allowed. Also, this CL instroduces
> an Object::SafeEquals() method which compares uncompressed values
> and thus is safe to be used for comparing Code with non-Code objects.
>
> Bug: v8:11880
> Change-Id: I7ccf1f90f927beb2bb9f45efb303e902b1838d02
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3838172
> Reviewed-by: Jakob Linke <jgruber@chromium.org>
> Reviewed-by: Camillo Bruni <cbruni@chromium.org>
> Reviewed-by: Dominik Inführ <dinfuehr@chromium.org>
> Commit-Queue: Igor Sheludko <ishell@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#82611}

Bug: v8:11880
Change-Id: Ie34af0135625eff2975f78f4d2901a76b8517eb7
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3842930
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Owners-Override: Leszek Swirski <leszeks@chromium.org>
Auto-Submit: Leszek Swirski <leszeks@chromium.org>
Cr-Commit-Position: refs/heads/main@{#82616}