Make new StreamController be async by default.

sdk/lib/io/http_impl.dart

 // Copyright (c) 2013, 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;
 
 class _HttpIncoming extends Stream<List<int>> {
   final int _transferLength;
   final Completer _dataCompleter = new Completer();
   Stream<List<int>> _stream;
@@ skipping 542 matching lines @@
   void _cancel() {
     if (_subscription != null) {
       StreamSubscription subscription = _subscription;
       _subscription = null;
       subscription.cancel();
     }
   }
 
   _ensureController() {
     if (_controller != null) return;
-    _controller = new StreamController(onPause: () => _subscription.pause(),
+    _controller = new StreamController(sync: true,
+                                       onPause: () => _subscription.pause(),
                                        onResume: () => _subscription.resume(),
                                        onListen: () => _subscription.resume(),
                                        onCancel: _cancel);
     _outbound._addStream(_controller.stream)
         .then((_) {
                 _cancel();
                 _done();
                 _closeCompleter.complete(_outbound);
               },
               onError: (error) {
@@ skipping 1348 matching lines @@
   // Indicated if the http server has been closed.
   bool closed = false;
 
   // The server listen socket.
   final ServerSocket _serverSocket;
   final bool _closeServer;
 
   // Set of currently connected clients.
   final Set<_HttpConnection> _connections = new Set<_HttpConnection>();
   final StreamController<HttpRequest> _controller
-      = new StreamController<HttpRequest>();
+      = new StreamController<HttpRequest>(sync: true);
 
   // TODO(ajohnsen): Use close queue?
 }
 
 
 class _ProxyConfiguration {
   static const String PROXY_PREFIX = "PROXY ";
   static const String DIRECT_PREFIX = "DIRECT";
 
   _ProxyConfiguration(String configuration) : proxies = new List<_Proxy>() {
@@ skipping 385 matching lines @@
 
 
 class _RedirectInfo implements RedirectInfo {
   const _RedirectInfo(int this.statusCode,
                       String this.method,
                       Uri this.location);
   final int statusCode;
   final String method;
   final Uri location;
 }