The DOMParser object doesn't report parsing errors. The following will cause a parser error in both Firefox and Opera: var xmldom = (new DOMParser()).parseFromString("<xml>", "text/xml"); The returned value is a document whose document element is <parseerror/> in Firefox and Opera; in WebKit it is <xml/> and no error occurs.
I cannot reproduce this. Try entering the following into the address bar: javascript:alert((new XMLSerializer).serializeToString((new DOMParser()).parseFromString("<xml>", "text/xml")))
Perhaps my original subject was incorrect. In Opera and FF, the <parsererror> element is the document element. In WebKit, it's inserted at the point of the parser error. This seems like a bug that should be fixed for interoperability.
*** This bug has been marked as a duplicate of 13057 ***
Mass moving XML DOM bugs to the "DOM" Component.