1 This test checks whether serialized invalid XHTML is valid XML (for bug 9901).
3 If the test passes, you'll see a series of 'PASS' messages below.
5 PASS: doc.firstChild.firstChild.nodeValue should be 123 and is.
6 PASS: str should be <input xmlns="http://www.w3.org/1999/xhtml">123</input> and is.