This reverts commit 916eb869.

Reason for revert: https://ci.chromium.org/ui/p/v8/builders/ci/V8%20Linux%20gcc/11805/overview

Original change's description:
> Reland "[wasm][bug] Fix a couple of bugs in validation of unreachable code"
>
> This is a reland of 4a037f87
>
> Changes compared to original change: None. This seems not to create
> problems after all.
>
> Original change's description:
> > [wasm][bug] Fix a couple of bugs in validation of unreachable code
> >
> > Changes:
> > - SetBlockType now instantiates the block's start merge with values of
> >   the correct type in unreachable code.
> > - EnsureStackArguments now keeps the existing stack values and moves
> >   them over the new bottom values.
> > - Drop stack size validation in Drop().
> > - Add new tests in unreachable-validation.js.
> >
> > Change-Id: Ie68b3d9abb0a41d1623d4a123fb526e71941c4e7
> > Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2902733
> > Commit-Queue: Manos Koukoutos <manoskouk@chromium.org>
> > Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
> > Cr-Commit-Position: refs/heads/master@{#74650}
>
> Change-Id: Id620f7fb6677b772b0dcfd38108256384db44439
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2905598
> Reviewed-by: Manos Koukoutos <manoskouk@chromium.org>
> Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
> Commit-Queue: Manos Koukoutos <manoskouk@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#74677}

Tbr: manoskouk@chromium.org
Change-Id: Ia24aa453735464bdd3aafca4617beabb0cbf8823
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2917601
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Auto-Submit: Jakob Gruber <jgruber@chromium.org>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Reviewed-by: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#74771}