aChange all asyncTest/callbackDone style tests to use the new expectAsync/

tests/dom/xhr_test.dart

Index: tests/dom/xhr_test.dart
===================================================================
--- tests/dom/xhr_test.dart	(revision 7823)
+++ tests/dom/xhr_test.dart	(working copy)
@@ -5,18 +5,17 @@
 
 main() {
   useDomConfiguration();
-  asyncTest('XHR', 1, () {
+  test('XHR', () {
     XMLHttpRequest xhr = new XMLHttpRequest();
     // TODO: figure out how to place a resource file with fixed name alongside
     // the .html file.
     xhr.open('GET', 'MISSING-FILE', true);
-    xhr.addEventListener('readystatechange', (event) {
+    xhr.addEventListener('readystatechange', expectAsync1((event) {
         if (xhr.readyState == 4) {
           Expect.equals(0, xhr.status);
           Expect.stringEquals('', xhr.responseText);
-          callbackDone();
         }
-      }, true);
+      }), true);
     xhr.send();
   });
 }