Do some housekeeping in tools/testing/dart

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 3121 matching lines @@
       bool replaying = recordedInputFile != null;
 
       // When the graph building is finished, notify event listeners.
       _graph.events
           .where((event) => event is dgraph.GraphSealedEvent)
           .listen((event) {
         eventAllTestsKnown();
       });
 
       // Queue commands as they become "runnable"
-      var commandEnqueuer = new CommandEnqueuer(_graph);
+      new CommandEnqueuer(_graph);
 
       // CommandExecutor will execute commands
       var executor;
       if (recording) {
         executor = new RecordingCommandExecutor(new Path(recordingOutputFile));
       } else if (replaying) {
         executor = new ReplayingCommandExecutor(new Path(recordedInputFile));
       } else {
         executor = new CommandExecutorImpl(
             _globalConfiguration, maxProcesses, maxBrowserProcesses,
@@ skipping 66 matching lines @@
     }
   }
 
   void eventAllTestsDone() {
     for (var listener in _eventListener) {
       listener.allDone();
     }
     _allDone();
   }
 }