Add dependent commands at the front of the run queue to make the progress indicator more linear.

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 1590 matching lines @@
   CommandQueue(this.graph, this.enqueuer, this.executor,
                this._maxProcesses, this._maxBrowserProcesses, this._verbose) {
     var eventCondition = graph.events.where;
     eventCondition((event) => event is dgraph.StateChangedEvent)
         .listen((event) {
           if (event.to == dgraph.NodeState.Enqueuing) {
             assert(event.from == dgraph.NodeState.Initialized ||
                    event.from == dgraph.NodeState.Waiting);
             graph.changeState(event.node, dgraph.NodeState.Processing);
             var command = event.node.userData;
-            _runQueue.add(command);
+            if (event.node.dependencies.length > 0) {
+              _runQueue.addFirst(command);
+            } else {
+              _runQueue.add(command);
+            }
             Timer.run(() => _tryRunNextCommand());
           }
     });
     eventCondition((event) => event is dgraph.GraphSealedEvent).listen((_) {
       _checkDone();
     });
   }
 
   Stream<CommandOutput> get completedCommands => _commandOutputStream.stream;
 
@@ skipping 441 matching lines @@
     }
   }
 
   void eventAllTestsDone() {
     for (var listener in _eventListener) {
       listener.allDone();
     }
     _allDone();
   }
 }