The main difference is that removals get processed before other
observers, like PresShell does. This prevents the options list from
getting re-filled, see the stack in the bug.
While at it, simplify the aria attribute notifications, they don't need
to walk the whole chain, as only DocAccessible cares about it. Route
them through the accessible service like the AttrElement ones.
Differential Revision: https://phabricator.services.mozilla.com/D304716
Emilio Cobos Álvarez
1ffa4bb822