Revert "Revert "Make stdout/stderr async""

pkg/analysis_server/lib/src/server/stdio_server.dart

 // Copyright (c) 2014, 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.
 
 library stdio.server;
 
 import 'dart:async';
 import 'dart:io';
 
 import 'package:analysis_server/src/channel/byte_stream_channel.dart';
@@ skipping 18 matching lines @@
   StdioAnalysisServer(this.socketServer);
 
   /**
    * Begin serving requests over stdio.
    *
    * Return a future that will be completed when stdin closes.
    */
   Future serveStdio() {
     ByteStreamServerChannel serverChannel = new ByteStreamServerChannel(
         stdin,
-        stdout.nonBlocking,
+        stdout,
         socketServer.instrumentationService);
     socketServer.createAnalysisServer(serverChannel);
     return serverChannel.closed;
   }
 }