The accessible name computation spec has changed to explicitly mention
this case:
Step 2A. Hidden Not Referenced. If the current node is hidden and is:
- Not part of an aria-labelledby or aria-describedby traversal, where
the node directly referenced by that relation was hidden.
- Nor part of a native host language text alternative element (e.g.
label in HTML) or attribute traversal, where the root of that traversal
was hidden.
See https://w3c.github.io/accname/#computation-steps. Chromium, Firefox
and Safari all agree with the spec.
Fixes#29796.