anchor.diff:      _ensureMembers();
       return new AsFilteredImmutableMap<String, MemberMirror, MethodMirror>(
           _members,
  -        (MemberMirror member) => member is MethodMirror);
  +        (MemberMirror member) => member is MethodMirror ? member : null);
     }
   
     Map<String, MethodMirror> get getters {
  
positive.code:     return new AsFilteredImmutableMap<String, MemberMirror, MethodMirror>(
          _members,
          (MemberMirror member) =>
              member is MethodMirror && (member as MethodMirror).isGetter);
    }
  
    Map<String, MethodMirror> get setters {
  
negative.code:     return new AsFilteredImmutableMap<String, MemberMirror, MethodMirror>(
          _members,
          (MemberMirror member) =>
              member is MethodMirror && (member as MethodMirror).isSetter ?
                  member : null);
    }
  
    Map<String, VariableMirror> get variables {
      _ensureMembers();
      return new AsFilteredImmutableMap<String, MemberMirror, VariableMirror>(
          _members,
          (MemberMirror member) => member is VariableMirror ? member : null);
    }
  }
  
  