anchor.diff:      _disposer.dispose();
     }
   
  -  focusFirst() {
  +  void focusFirst() {
       _focusFirstInOrder(
           new DomTreeIterator(_content.element, scope: _content.element));
     }
   
  -  focusLast() {
  +  void focusLast() {
       _focusFirstInOrder(new DomTreeIterator(_content.element,
           scope: _content.element, reverse: true, wraps: true));
     }
   
  -  _focusFirstInOrder(Iterator<Element> iterator) {
  +  void _focusFirstInOrder(Iterator<Element> iterator) {
       while (iterator.moveNext()) {
         if (iterator.current.tabIndex == 0 && _visible(iterator.current)) {
           iterator.current.focus();
  
positive.code:     return (element.offsetWidth != 0 && element.offsetHeight != 0);
    }
  
    _focusDefault() {
      if (_autoFocusDirective != null) {
        _autoFocusDirective.focus();
      } else if (_content != null) {
  
negative.code: 
  @Directive(
    selector: '[focusContentWrapper]',
  )
  class FocusContentWrapper extends FocusableDirective {
    Element _element;
  