Upgrading tests with unittest deprecations

tests/isolate/illegal_msg_mirror_test.dart

Index: tests/isolate/illegal_msg_mirror_test.dart
diff --git a/tests/isolate/illegal_msg_mirror_test.dart b/tests/isolate/illegal_msg_mirror_test.dart
index dcf80a01d6d480bd0925efbbe3e22a3103bc1953..c739256996636acbcac2594e5e367a4ba6234a16 100644
--- a/tests/isolate/illegal_msg_mirror_test.dart
+++ b/tests/isolate/illegal_msg_mirror_test.dart
@@ -32,7 +32,7 @@ void main([args, port]) {
     Future spawn = Isolate.spawn(echo, port.sendPort);
     var caught_exception = false;
     var stream = port.asBroadcastStream();
-    stream.first.then(expectAsync1((snd) {
+    stream.first.then(expectAsync((snd) {
       try {
         snd.send(methodMirror);
       } catch (e) {
@@ -42,7 +42,7 @@ void main([args, port]) {
       if (caught_exception) {
         port.close();
       } else {
-        stream.first.then(expectAsync1((msg) {
+        stream.first.then(expectAsync((msg) {
           print("from worker ${msg}");
         }));
       }