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

samples/swarm/test/swarm_ui_lib/layout/grid_examples.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.
 
 part of layout_tests;
 
 /**
  * The examples from the spec: [http://dev.w3.org/csswg/css3-grid-align/]
  */
 // I've omitted examples that are subsumed by other examples, or examples
@@ skipping 14 matching lines @@
     '7 Grid Cells': GridCells.selectors,
     '11a Starting and Ending Grid Lines': StartEndingGridlines11a.selectors,
     '11b Starting and Ending Grid Lines': StartEndingGridlines11b.selectors,
     '12 Repeating Columns and Rows': RepeatingColumnsRows.selectors,
     '17 Anonymous Grid Cells': AnonymousGridCells.selectors,
     '20 Implicit Columns and Rows': ImplicitColumnsRows.selectors,
     '22 Grid Item Alignment': AlignGridItems.selectors,
     '23 Drawing Order of Grid Items': DrawOrderGridItems.selectors
   };
 }