anchor.diff:  
     group('innerHtml', () {
       test('query', () {
  -      document.register('x-type8', CustomType);
  +      var tag = nextTag;
  +      document.register(tag, CustomType);
         var element = new DivElement();
  -      element.innerHtml = '<x-type8></x-type8>';
  +      element.innerHtml = '<$tag></$tag>';
         document.body.nodes.add(element);
  -      var queried = query('x-type8');
  +      var queried = query(tag);
   
         expect(queried, isNotNull);
         expect(queried is CustomType, isTrue);
  
positive.code:         firedOnPre = true;
        });
  
        document.register('x-type7', CustomType);
  
        var postElement = dom.children[0];
        expect(postElement, isNotNull);
  
negative.code: import '../../pkg/unittest/lib/html_individual_config.dart';
  import 'dart:html';
  
  class CustomMixin {
    var mixinMethodCalled;
  
    void mixinMethod() {
      mixinMethodCalled = true;
    }
  }
  
  class CustomType extends HtmlElement with CustomMixin{
    factory CustomType() => null;
    bool onCreatedCalled; // = false;
    void onCreated() {
      onCreatedCalled = true;
      customCreatedCount++;
    }
  
    void invokeMixinMethod() {
      mixinMethod();
    }
  }
  
  int customCreatedCount = 0;
  
  int nextTagId = 0;
  String get nextTag => 'x-type${nextTagId++}';
  
  class NotAnElement {}
  
  