DOMBuilderTest1-4 in L3 L&S and other tests can not be written using the 
existing assertDOMException construct.  In DOMBuilderTest1-4, parseWithContext 
can either throw a NOT_SUPPORTED_ERR or perform the requested action.  Other 
tests may have multiple allowable return codes which this construct would 
support, though it would be better to rewrite the test so that only one error 
in applicable.

Basically,

<try>
    <!--  one or more statements  -->
    <catch>
         <!--  one of more exception clauses   -->
         <DOMException code="NOT_SUPPORTED_ERR">
              <!--  one or more statements   -->
         </DOMException>
    </catch>
</try>