anchor.diff:  /// If multiple platforms match, the annotations apply in order as through
   /// they were in nested groups.
   void group(description, body(),
  -    {String testOn,
  -    Timeout timeout,
  -    skip,
  -    tags,
  -    Map<String, dynamic> onPlatform}) =>
  -  description == null
  -      ? _declarer.group(description, body,
  -          testOn: testOn, timeout: timeout, skip: skip, tags: tags)
  -      : _declarer.group(description.toString(), body,
  -          testOn: testOn, timeout: timeout, skip: skip, tags: tags);
  -
  +        {String testOn,
  +        Timeout timeout,
  +        skip,
  +        tags,
  +        Map<String, dynamic> onPlatform}) =>
  +    _declarer.group(description.toString(), body,
  +        testOn: testOn, timeout: timeout, skip: skip, tags: tags);
   
   /// Registers a function to be run before tests.
   ///
  
positive.code: 
  // TODO(nweiz): This and other top-level functions should throw exceptions if
  // they're called after the declarer has finished declaring.
  /// Creates a new test case with the given description and body.
  ///
  /// The description will be added to the descriptions of any surrounding
  /// [group]s. If [testOn] is passed, it's parsed as a [platform selector][]; the
  
negative.code: 
  /// Creates a group of tests.
  ///
  /// A group's description (converted to a string) is included in the descriptions
  /// of any tests or sub-groups it contains. [setUp] and [tearDown] are also scoped
  /// to the containing group.
  ///
  /// If [testOn] is passed, it's parsed as a [platform selector][]; the test will
  /// only be run on matching platforms.
  