not part of build. Now that null DOM strings are correctly supported we can fix the test case

js/src/xpconnect/tests/js/old/xpctest_echo.js

@@ -241,7 +241,7 @@ print("EchoIn2OutOneDOMString of empty string - "+(
        ? "passed" : "failed"));
 
 print("EchoIn2OutOneDOMString of null - "+(
-       echo.EchoIn2OutOneDOMString(null) == "null"
+       echo.EchoIn2OutOneDOMString(null) == null
        ? "passed" : "failed"));
 
 print("EchoIn2OutOneDOMString of undefined - "+(