Let test-runner wait for stdout & stderr when running tests.

tools/testing/dart/test_runner.dart

 // Copyright (c) 2012, 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.
 
 /**
  * Classes and methods for executing tests.
  *
  * This module includes:
  * - Managing parallel execution of tests, including timeout checks.
  * - Evaluating the output of each test as pass/fail/crash/timeout.
@@ skipping 1344 matching lines @@
                              environment: processEnvironment);
         processFuture.then((io.Process process) {
           // Close stdin so that tests that try to block on input will fail.
           process.stdin.close();
           void timeoutHandler() {
             timedOut = true;
             if (process != null) {
               process.kill();
             }
           }
-          process.exitCode.then(_commandComplete);
-          _drainStream(process.stdout, stdout);
-          _drainStream(process.stderr, stderr);
+          Future.wait([process.exitCode,
+                       _drainStream(process.stdout, stdout),
+                       _drainStream(process.stderr, stderr)])
+              .then((values) => _commandComplete(values[0]));
           timeoutTimer = new Timer(new Duration(seconds: timeout),
                                    timeoutHandler);
         }).catchError((e) {
           // TODO(floitsch): should we try to report the stacktrace?
           print("Process error:");
           print("  Command: $command");
           print("  Error: $e");
           _commandComplete(-1);
           return true;
         });
@@ skipping 14 matching lines @@
         command,
         exitCode,
         timedOut,
         stdout,
         stderr,
         new DateTime.now().difference(startTime),
         compilationSkipped);
     return commandOutput;
   }
 
-  void _drainStream(Stream<List<int>> source, List<int> destination) {
-    source.listen(destination.addAll);
+  Future _drainStream(Stream<List<int>> source, List<int> destination) {
+    return source.listen(destination.addAll).asFuture();
   }
 
   Map<String, String> _createProcessEnvironment() {
     var environment = io.Platform.environment;
 
     if (command.environmentOverrides != null) {
       for (var key in command.environmentOverrides.keys) {
         environment[key] = command.environmentOverrides[key];
       }
     }
@@ skipping 966 matching lines @@
     }
   }
 
   void eventAllTestsDone() {
     for (var listener in _eventListener) {
       listener.allDone();
     }
     _allDone();
   }
 }