Register a callback when an HTMLElement attribute changes.
This is used, for example, by the Skybox component to watch for changes to the environment-* and skybox-* attributes.
Duplicate registrations of the same (element, name, callback) triple are
silently skipped — the callback is only added once and the returned
unsubscribe function still removes it correctly.
Register a callback when an HTMLElement attribute changes. This is used, for example, by the Skybox component to watch for changes to the environment-* and skybox-* attributes. Duplicate registrations of the same (element, name, callback) triple are silently skipped — the callback is only added once and the returned unsubscribe function still removes it correctly.