Mark visually hidden tree nodes in getAccessibilityTree

[calebeby]

(I am thinking this through so this is not a complete thought yet, hold off on feedback till I finish the thought)

Accessible by screen readers, Visible by sighted users How to test Shows up in accessibility tree without (visually hidden) marker	Accessible by screen readers, Hidden from sighted users .sr-only, .u-visually-hidden, etc How to test Shows up in accessibility tree with (visually hidden) marker
Hidden from screen readers, Visible by sighted users aria-hidden	Hidden from screen readers, Hidden from sighted users Removed from the DOM display:none etc