chromium/third_party/blink/web_tests/editing/style/invalid-font-size.html

<!DOCTYPE html>
<html>
<body>
<script src="../../resources/dump-as-markup.js"></script>
<div id="test" contenteditable><font size="x">hello</font></div>
<script>

Markup.description('This tests applying font size to text inside a font element with an invalid size attribute.\n' + 
'WebKit should not crash and there should be exactly one font element with size="4"')
var test = document.getElementById('test');
window.getSelection().selectAllChildren(test);
document.execCommand('fontSize', false, '4');
Markup.dump(test);

</script>
</body>
</html>