] && textContentModel[outer].comments
          && !(textContentModel[inner] && textContentModel[inner].unended)) {
        var stack = containmentStackFor(outer, [inner]);
        if (stack) {
          // <outer><inner></inner><!--After inner --></outer>
          return tagStackToHtml(
              stack, '<' + inner + '></' + inner + '><!-- After inner -->');
        }
      }
      return null;
    }

    function check(outer, inner, body, result) {
      var outerEl = body.getElementsByTagName(outer)