Migrate dom tests to dart:html.

client/tests/client/dom/XHRTest.dart

Index: client/tests/client/dom/XHRTest.dart
diff --git a/client/tests/client/dom/XHRTest.dart b/client/tests/client/dom/XHRTest.dart
index 758dfb6d3f57539b5d8012229de700413e6f7729..acdb0dfc2832366feaf66ffa7730eca36ae7b711 100644
--- a/client/tests/client/dom/XHRTest.dart
+++ b/client/tests/client/dom/XHRTest.dart
@@ -1,16 +1,16 @@
 #library('XHRTest');
 #import('../../../../lib/unittest/unittest.dart');
-#import('../../../../lib/unittest/dom_config.dart');
-#import('dart:dom');
+#import('../../../../lib/unittest/html_config.dart');
+#import('dart:html');
 
 main() {
-  useDomConfiguration();
+  useHtmlConfiguration();
   asyncTest('XHR', 1, () {
     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.on.readyStateChange.add((event) {
         if (xhr.readyState == 4) {
           Expect.equals(0, xhr.status);
           Expect.stringEquals('', xhr.responseText);