Make new StreamController be async by default.

tests/standalone/io/web_socket_protocol_processor_test.dart

 // Copyright (c) 2012, 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 "package:expect/expect.dart";
 import "dart:utf";
 import "dart:math";
 import "dart:async";
 import "dart:collection";
 import "dart:typed_data";
@@ skipping 83 matching lines @@
   return frame;
 }
 
 
 // Test processing messages which are sent in a single frame.
 void testFullMessages() {
   void testMessage(int opcode, List<int> message) {
     int messageCount = 0;
     // Use the same web socket protocol transformer for all frames.
     var transformer = new _WebSocketProtocolTransformer();
-    var controller = new StreamController();
+    var controller = new StreamController(sync: true);
     WebSocketMessageCollector mc = new WebSocketMessageCollector(
         controller.stream.transform(transformer),
         message);
 
     List<int> frame = createFrame(
         true, opcode, null, message, 0, message.length);
 
     // Update the transformer with one big chunk.
     messageCount++;
     controller.add(frame);
@@ skipping 43 matching lines @@
   runTest(120, 130, 1);
   runTest(0, 1000, 100);
   runTest(65534, 65537, 1);
 }
 
 
 // Test processing of frames which are split into fragments.
 void testFragmentedMessages() {
   // Use the same web socket protocol transformer for all frames.
   var transformer = new _WebSocketProtocolTransformer();
-  var controller = new StreamController();
+  var controller = new StreamController(sync: true);
   WebSocketMessageCollector mc = new WebSocketMessageCollector(
       controller.stream.transform(transformer));
 
   int messageCount = 0;
   int frameCount = 0;
 
   void testFragmentMessage(int opcode, List<int> message, int fragmentSize) {
     messageCount++;
     int messageIndex = 0;
     int remaining = message.length;
@@ skipping 44 matching lines @@
   runTest(0, 10, 1);
   runTest(120, 130, 1);
   runTest(0, 1000, 100);
   runTest(65534, 65537, 1);
   print("Fragment messages test, messages $messageCount, frames $frameCount");
   Expect.equals(messageCount, mc.messageCount);
 }
 
 void testUnmaskedMessage() {
   var transformer = new _WebSocketProtocolTransformer(true);
-  var controller = new StreamController();
+  var controller = new StreamController(sync: true);
   var port = new ReceivePort();
   controller.stream.transform(transformer).listen((_) {}, onError: (e) {
     port.close();
   });
   var message = new Uint8List(10);
   List<int> frame = createFrame(
       true, FRAME_OPCODE_BINARY, null, message, 0, message.length);
   controller.add(frame);
 }
 
 
 void main() {
   testFullMessages();
   testFragmentedMessages();
   testUnmaskedMessage();
 }