Revert "Revert "Make stdout/stderr async""

tests/standalone/io/stdout_stderr_non_blocking_test.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.
-
-import "package:expect/expect.dart";
-import "dart:async";
-import "dart:convert";
-import "dart:io";
-
-callIOSink(IOSink sink) {
-  // Call all methods on IOSink.
-  sink.encoding = ASCII;
-  Expect.equals(ASCII, sink.encoding);
-  sink.write("Hello\n");
-  sink.writeln("Hello");
-  sink.writeAll(["H", "e", "l", "lo\n"]);
-  sink.writeCharCode(72);
-  sink.add([101, 108, 108, 111, 10]);
-
-  var controller = new StreamController(sync: true);
-  var future = sink.addStream(controller.stream);
-  controller.add([72, 101, 108]);
-  controller.add([108, 111, 10]);
-  controller.close();
-
-  future.then((_) {
-    controller = new StreamController(sync: true);
-    controller.stream.pipe(sink);
-    controller.add([72, 101, 108]);
-    controller.add([108, 111, 10]);
-    controller.close();
-  });
-}
-
-main() {
-  callIOSink(stdout.nonBlocking);
-  stdout.nonBlocking.done.then((_) {
-    callIOSink(stderr.nonBlocking);
-    stderr.nonBlocking.done.then((_) {
-      stdout.close();
-      stderr.close();
-    });
-  });
-}