Cleaning up the TableElement API

tools/dom/templates/html/dart2js/impl_HTMLTableElement.darttemplate

-// 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.
-
-part of $LIBRARYNAME;
-
-$(ANNOTATIONS)class $CLASSNAME$EXTENDS$IMPLEMENTS$NATIVESPEC {
-$!MEMBERS
-
-  Element createTBody() {
-    if (JS('bool', '!!#.createTBody', this)) {
-      return this._createTBody();
-    }
-    var tbody = new Element.tag('tbody');
-    this.children.add(tbody);
-    return tbody;
-  }
-
-  @JSName('createTBody')
-  Element _createTBody() native;
-}