Reorganize tests for samples so the test is discoverable from the sample

samples/swarm/test/swarm_ui_lib/layout/layout_test.dart

 // Copyright (c) 2011, 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 layout_tests;
 
 import 'package:expect/expect.dart';
 import 'dart:async';
 import 'dart:html';
-import '../../../../swarm/swarm_ui_lib/base/base.dart';
-import '../../../../swarm/swarm_ui_lib/layout/layout.dart';
-import '../../../../swarm/swarm_ui_lib/view/view.dart';
-import '../../../../swarm/swarm_ui_lib/util/utilslib.dart';
-import '../../../../../pkg/unittest/lib/unittest.dart';
-import '../../../../../pkg/unittest/lib/html_config.dart';
+import '../../../swarm_ui_lib/base/base.dart';
+import '../../../swarm_ui_lib/layout/layout.dart';
+import '../../../swarm_ui_lib/view/view.dart';
+import '../../../swarm_ui_lib/util/utilslib.dart';
+import 'package:unittest/html_config.dart';
+import 'package:unittest/unittest.dart';
 
 part 'grid_layout_demo.dart';
 part 'grid_examples.dart';
 part 'css.dart';
 
 // TODO(jmesserly): these tests would be easier to work with if they were WebKit
 // layout tests. The way content shell works is exactly what we want for
 // testing layout: run the example and then print the element tree with metrics.
 // The UnitTestSuite wrapper gets in our way here, because you can't "see" the
 // test layout visually when you're debugging.
@@ skipping 158 matching lines @@
       Expect.equals(values[1], node.offsetTop);
       Expect.equals(values[2], node.offsetWidth);
       Expect.equals(values[3], node.offsetHeight);
     });
   }
 }
 
 Future verifyExample(String example, [Map expected = null]) {
   return usingGrid(example, (grid) => verifyGrid(example, expected));
 }