cleanup to tools/testing/dart

tests/standalone/io/dependency_graph_test.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.
 
 import 'package:expect/expect.dart';
 
-import '../../../tools/testing/dart/dependency_graph.dart' as graph;
+import '../../../tools/testing/dart/lib/dependency_graph.dart' as graph;
 
 main() {
   var dgraph = new graph.Graph();
   var numberOfEvents = 0;
   var eventAssertions = [];
 
   graph.Node newNode(int i, List deps) {
     graph.Node node = dgraph.newNode(i, deps);
     Expect.isTrue(node.userData == i);
     Expect.isTrue(dgraph.nodes.contains(node));
@@ skipping 35 matching lines @@
   node3 = newNode(3, [node1, node2]);
   changeState(node2, graph.NodeState.Failed);
   changeState(node3, graph.NodeState.UnableToRun);
 
   dgraph.events.take(numberOfEvents).toList().then((events) {
     for (var i=0; i<events.length; i++) {
       eventAssertions[i](events[i]);
     }
   });
 }