Move _HTMLElement to HtmlElement

tests/html/element_types_test.dart

 // Copyright (c) 2012, 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.
 
 library element_types;
 import '../../pkg/unittest/lib/unittest.dart';
 import '../../pkg/unittest/lib/html_individual_config.dart';
 import 'dart:html';
 
 main() {
@@ skipping 98 matching lines @@
     check('datalist', () => new DataListElement() is DataListElement,
         DataListElement.supported);
     check('dl', () => new DListElement() is DListElement);
     check('div', () => new DivElement() is DivElement);
     check('embed', () => new EmbedElement() is EmbedElement,
         EmbedElement.supported);
     check('fieldset', () => new FieldSetElement() is FieldSetElement);
     check('form', () => new FormElement() is FormElement);
     check('head', () => new HeadElement() is HeadElement);
     check('hr', () => new HRElement() is HRElement);
-    check('html', () => new HtmlElement() is HtmlElement);
+    check('html', () => new HtmlHtmlElement() is HtmlHtmlElement);
     check('h1', () => new HeadingElement.h1() is HeadingElement);
     check('h2', () => new HeadingElement.h2() is HeadingElement);
     check('h3', () => new HeadingElement.h3() is HeadingElement);
     check('h4', () => new HeadingElement.h4() is HeadingElement);
     check('h5', () => new HeadingElement.h5() is HeadingElement);
     check('h6', () => new HeadingElement.h6() is HeadingElement);
     check('iframe', () => new IFrameElement() is IFrameElement);
     check('img', () => new ImageElement() is ImageElement);
     check('input', () => new InputElement() is InputElement);
     check('keygen', () => new KeygenElement() is KeygenElement,
@@ skipping 49 matching lines @@
       test('accepts li', () {
         var ul = new UListElement();
         var li = new LIElement();
         ul.append(li);
       });
     });
     check('video', () => new VideoElement() is VideoElement);
     check('unknown', () => new Element.tag('someunknown') is UnknownElement);
   });
 }