The assert `Klass::is_valid(obj->klass())` is used in 2 places, but the underlying call to `ClassLoaderDataGraph::is_valid` requires

```
 # fatal error: must own lock ClassLoaderDataGraph_lock
 ```

which is not held in this flow.

The forward walk does not provide any stronger guarantees than the 2 asserts after it, and so the whole walk should be removed to reduce complexity.