This reverts commit ec4a3124.

Reason for revert: https://bugs.chromium.org/p/chromium/issues/detail?id=1253374#c2

Original change's description:
> heap: Resolve -Wshadow warning in allocation-observer.cc
>
> Bug: v8:12244, v8:12245
> Change-Id: Id6b9e0a3986fb04c1a949b26ecf20da652ddd097
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3181537
> Auto-Submit: Michael Lippautz <mlippautz@chromium.org>
> Reviewed-by: Dominik Inführ <dinfuehr@chromium.org>
> Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#77045}

Bug: v8:12244, v8:12245
Change-Id: I506055fa7b959ac9adffa77ebc58234ec5b03371
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3186834Reviewed-by: Sathya Gunasekaran  <gsathya@chromium.org>
Cr-Commit-Position: refs/heads/main@{#77100}