Make new StreamController be async by default.

sdk/lib/io/file_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;
 
 // Read the file in blocks of size 64k.
 const int _BLOCK_SIZE = 64 * 1024;
 
 
@@ skipping 29 matching lines @@
                                        {void onError(error),
                                         void onDone(),
                                         bool cancelOnError}) {
     return _controller.stream.listen(onData,
                                      onError: onError,
                                      onDone: onDone,
                                      cancelOnError: cancelOnError);
   }
 
   void _setupController() {
-    _controller = new StreamController<List<int>>(
+    _controller = new StreamController<List<int>>(sync: true,
         onListen: _start,
         onPause: () => _paused = true,
         onResume: _resume,
         onCancel: () {
           _unsubscribed = true;
           _closeFile();
         });
   }
 
   Future _closeFile() {
@@ skipping 420 matching lines @@
   }
 
   String readAsStringSync({Encoding encoding: Encoding.UTF_8}) {
     List<int> bytes = readAsBytesSync();
     return _decodeString(bytes, encoding);
   }
 
   static List<String> _decodeLines(List<int> bytes, Encoding encoding) {
     if (bytes.length == 0) return [];
     var list = [];
-    var controller = new StreamController();
+    var controller = new StreamController(sync: true);
     controller.stream
         .transform(new StringDecoder(encoding))
         .transform(new LineTransformer())
         .listen((line) => list.add(line));
     controller.add(bytes);
     controller.close();
     return list;
   }
 
   Future<List<String>> readAsLines({Encoding encoding: Encoding.UTF_8}) {
@@ skipping 475 matching lines @@
 
   Future _closedException() {
     return new Future.error(new FileIOException("File closed '$_path'"));
   }
 
   final String _path;
   int _id;
 
   SendPort _fileService;
 }