This reverts commit 9e1db518.

Reason for revert: https://chromium-review.googlesource.com/c/v8/v8/+/3535782 causes roll failures, this needs to be reverted too because it's based on it

Original change's description:
> cppgc: Add DCHECK that object start bitmap is safe to use
>
> During sweeeping/compaction the bitmap is being reconstructed and
> should not be relied on for finding object start.
> Add a DCHECK that the bitmap is fully populated.
>
> Bug: chromium:1307471
> Change-Id: I4aa414722262bb6fb169123a49fce1510a60d3ef
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3540680
> Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
> Commit-Queue: Omer Katz <omerkatz@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#79575}

Bug: chromium:1307471
Change-Id: I377b8737609fff33199776dce3d997f31074c59b
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3545316
Auto-Submit: Tobias Tebbi <tebbi@google.com>
Owners-Override: Tobias Tebbi <tebbi@google.com>
Commit-Queue: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Cr-Commit-Position: refs/heads/main@{#79586}