It is an invariant that objects in the shared heap never point into
per-Isolate heaps. This is currently broken by DependentCode. At the
same time, shared maps and other holders of DependentCode are designed
to never invalidate optimized code. E.g., shared maps are effectively
immutable.

This CL does two things:

1. Prevent shared objects from being depended upon
2. DCHECK that shared objects never cause deoptimization

Bug: v8:12547, v8:12761
Change-Id: I0fedae9134a8f786a9200e70f99dba7b38cd2d80
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3704809Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Shu-yu Guo <syg@chromium.org>
Cr-Commit-Position: refs/heads/main@{#81340}