Make new StreamController be async by default.

sdk/lib/io/secure_server_socket.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.
 
 part of dart.io;
 
 /**
  * The [SecureServerSocket] is a server socket, providing a stream of high-level
  * [Socket]s.
  *
@@ skipping 104 matching lines @@
   final bool requestClientCertificate;
   final bool requireClientCertificate;
   bool _closed = false;
 
   RawSecureServerSocket._(RawServerSocket serverSocket,
                           String this.certificateName,
                           bool this.requestClientCertificate,
                           bool this.requireClientCertificate) {
     _socket = serverSocket;
     _controller = new StreamController<RawSecureSocket>(
+        sync: true,
         onListen: _onSubscriptionStateChange,
         onPause: _onPauseStateChange,
         onResume: _onPauseStateChange,
         onCancel: _onSubscriptionStateChange);
   }
 
   /**
    * Returns a future for a [RawSecureServerSocket]. When the future
    * completes the server socket is bound to the given [address] and
    * [port] and has started listening on it.
@@ skipping 122 matching lines @@
       _subscription = _socket.listen(_onData,
                                      onDone: _onDone,
                                      onError: _onError);
     } else {
       close();
     }
   }
 }