cdfa0499f4
Now the accessibility for the single select box better matches what is picked up for a native select. This fixes an issue with us always setting `aria-activedescendant`, which caused Orca to always say the full path to the selected result, instead of saying that the box was a combobox with a selection. This means that the `aria-activedescendant` attribute will now only be set when the dropdown is open. This also switches the results list from a listbox to a tree, which is what Firefox tells screen readers that a standard select is. Combined with a change to use `role=group` and `aria-label` for option group labels, screen readers will now announce the group that they are in as well.