Fix the MultiChannel constructor.

test/multi_channel_test.dart

 // Copyright (c) 2016, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 import 'dart:async';
 
 import 'package:stream_channel/stream_channel.dart';
 import 'package:test/test.dart';
 
 import 'utils.dart';
 
 void main() {
   var oneToTwo;
   var twoToOne;
   var channel1;
   var channel2;
   setUp(() {
     oneToTwo = new StreamController();
     twoToOne = new StreamController();
-    channel1 = new MultiChannel(twoToOne.stream, oneToTwo.sink);
-    channel2 = new MultiChannel(oneToTwo.stream, twoToOne.sink);
+    channel1 = new MultiChannel(
+        new StreamChannel(twoToOne.stream, oneToTwo.sink));
+    channel2 = new MultiChannel(
+        new StreamChannel(oneToTwo.stream, twoToOne.sink));
   });
 
   group("the default virtual channel", () {
     test("begins connected", () {
       var first = true;
       channel2.stream.listen(expectAsync((message) {
         if (first) {
           expect(message, equals("hello"));
           first = false;
         } else {
@@ skipping 269 matching lines @@
     test("emits an error, the error is sent only to the default channel", () {
       channel1.stream.listen(expectAsync((_) {}, count: 0),
           onError: expectAsync((error) => expect(error, equals("oh no"))));
       virtual1.stream.listen(expectAsync((_) {}, count: 0),
           onError: expectAsync((_) {}, count: 0));
 
       twoToOne.addError("oh no");
     });
   });
 }