Allow 'empty' tests if a feature is not supported in the browser.

pkg/unittest/lib/html_individual_config.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.
 
 /**
  * A unit test library for running groups of tests in a browser, instead of the
  * entire test file. This is especially used for large tests files that have
  * many subtests, so we can mark groups as failing at a finer granularity than
  * the entire test file.
  *
@@ skipping 19 matching lines @@
 
       if(!groups.isEmpty) {
         if(groups.length > 1) {
           throw 'More than one "group" parameter provided.';
         }
 
         var testGroupName = groups.single.split('=')[1];
         var startsWith = "$testGroupName${unittest.groupSep}";
         unittest.filterTests((unittest.TestCase tc) =>
             tc.description.startsWith(startsWith));
-
-
-        /*if(unittest.testCases.isEmpty) {
-          throw 'No tests match group "$testGroupName".';
-        }*/
       }
     }
     super.onStart();
   }
 }
 
 void useHtmlIndividualConfiguration([bool isLayoutTest = false]) {
   unittest.unittestConfiguration = isLayoutTest ? _singletonLayout : _singletonNotLayout;
 }
 
 final _singletonLayout = new HtmlIndividualConfiguration(true);
 final _singletonNotLayout = new HtmlIndividualConfiguration(false);