AX: aria-expanded="undefined" is exposed as AXExpanded:NO. WebKit should not expose AXExpanded when aria-expanded is anything other than "true" or "false", except on roles where it is a required attr, which is only combobox in ARIA 1.0. Test file https://dvcs.w3.org/hg/pfwg/raw-file/default/ARIA/1.0/tests/test-files/roles-properties-supported-inherited/roles-properties-supported-inherited-alertdialog-aria-expanded-undefined.html
<rdar://problem/13735009>
*** This bug has been marked as a duplicate of bug 113895 ***