role=tree without children triggering axe error #456
Description
Using ace 1.3.7. with, e.g.
<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml" xmlns:epub="http://www.idpf.org/2007/ops">
<head>
<title>tree without children test</title>
</head>
<body>
<div role="tree" aria-label="no children"> </div>
</body>
</html>triggers an aria-required-children error in axe ("Required ARIA children role not present: group, treeitem" etc). However, that's no longer a requirement in ARIA 1.3.
(Using a recent version, axe itself does not seem to complain about this either so perhaps ace's axe fork just needs an update.)