- Use more HeapObject instead of Object
- Use raw instance_type

Bug: v8:11525
Change-Id: I5f1b8ea95fa14acc9c94555a95e8586f3c7e8888
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3422637Reviewed-by: Marja Hölttä <marja@chromium.org>
Commit-Queue: Camillo Bruni <cbruni@chromium.org>
Cr-Commit-Position: refs/heads/main@{#78835}