AX: Fix shadow DOM focusability once HTML specifies the right way to do so W3C HTML: https://www.w3.org/Bugs/Public/show_bug.cgi?id=23870 WHATWG: https://www.w3.org/Bugs/Public/show_bug.cgi?id=24106
Actually, duping this out to bug 117857. *** This bug has been marked as a duplicate of bug 117857 ***