Enable wrapper-less browser tests on selenium.

dart/tests/html/js_interop_1_test.dart

Index: dart/tests/html/js_interop_1_test.dart
diff --git a/dart/tests/html/js_interop_1_test.dart b/dart/tests/html/js_interop_1_test.dart
index a2d0aba91bb56894edb2b9d6fca50fb55adda205..e63322d065e9a12d3300fa9f3d513ebf24d5b073 100644
--- a/dart/tests/html/js_interop_1_test.dart
+++ b/dart/tests/html/js_interop_1_test.dart
@@ -20,10 +20,14 @@ main() {
   var callback;
 
   test('js-to-dart-post-message', () {
-    callback = expectAsync1((e) {
-      Expect.equals('hello', e.data);
+    var onSuccess = expectAsync1((e) {
       window.on.message.remove(callback);
     });
+    callback = (e) {
+      if (e.data == 'hello') {
+        onSuccess(e);
+      }
+    };
     window.on.message.add(callback);
     injectSource("window.postMessage('hello', '*');");
   });