DOMException toString is not correct

LayoutTests/fast/dom/DOMException/resources/XPathException.js

 description("Tests the properties of the XPathException object.")
 
 var e;
 try {
     var evalulator = new XPathEvaluator;
     var nsResolver = evalulator.createNSResolver(document);
     var result = evalulator.evaluate("/body", document, nsResolver, 0, null);
     var num = result.numberValue;
    // raises a TYPE_ERR
 } catch (err) {
     e = err;
 }
 
-shouldBeEqualToString("e.toString()", "Error: TYPE_ERR: DOM XPath Exception 52");
+shouldBeEqualToString("e.toString()", "TYPE_ERR: The expression could not be converted to return the specified type.");
 shouldBeEqualToString("Object.prototype.toString.call(e)", "[object XPathException]");
 shouldBeEqualToString("Object.prototype.toString.call(e.__proto__)", "[object XPathExceptionPrototype]");
 shouldBeEqualToString("e.constructor.toString()", "function XPathException() { [native code] }");
 shouldBe("e.constructor", "window.XPathException");
 shouldBe("e.TYPE_ERR", "e.constructor.TYPE_ERR");
 shouldBe("e.INVALID_EXPRESSION_ERR", "51");
 shouldBe("e.TYPE_ERR", "52");