[dart:io] flush() stdin before close()ing

tools/testing/dart/android.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.
 
 library android;
 
 import "dart:async";
 import "dart:convert" show LineSplitter, UTF8;
 import "dart:core";
 import "dart:collection";
@@ skipping 37 matching lines @@
   Future<String> getOutput(Stream<List<int>> stream) {
     return stream
         .transform(UTF8.decoder)
         .toList()
         .then((data) => data.join(""));
   }
 
   return Process.start(executable, args).then((Process process) async {
     if (stdin != null && stdin != '') {
       process.stdin.write(stdin);
+      await process.stdin.flush();
     }
     process.stdin.close();
 
     Timer timer;
     bool timedOut = false;
     if (timeout != null) {
       timer = new Timer(timeout, () {
         timedOut = true;
         process.kill(ProcessSignal.SIGTERM);
         timer = null;
@@ skipping 362 matching lines @@
 
   void releaseDevice(AdbDevice device) {
     if (_waiter.length > 0) {
       Completer completer = _waiter.removeFirst();
       completer.complete(device);
     } else {
       _idleDevices.add(device);
     }
   }
 }