anchor.diff:    bool get showing => _visible && !_outlineDiv.classes.contains('collapsed');
   
     void setFontSize(num size) {
  -    List ss = html.document.styleSheets;
  -    ss.forEach((s) {
  -      s.cssRules.forEach((r) {
  -        if (r is html.CssStyleRule && r.selectorText == '.${ITEM_CSS_CLASS}') {
  -          r.style.height = '${size + 2}px';
  -        }
  -      });
  -    });
       _rootList.style.fontSize = '${size}px';
  +    // Outline items are created dynamically, so we can't just modify element's
  +    // style: we have to modify the CSS rule that applies to all items.
  +    _outlineItemCssRules.forEach((rule) => rule.style.height = '${size}px');
     }
   
     /**
  
positive.code:       _element.append(_typeSpan);
      }
  
      _element.classes.add("${Outline.ITEM_CSS_CLASS} ${cssClassName}");
    }
  
    String get displayName => _data.name;
  
negative.code:         _outlineDiv.classes.add('collapsed');
        }
      });
  
      html.document.styleSheets.forEach((sheet) {
        final Iterable<html.CssStyleRule> rules = sheet.cssRules.where((rule) {
          return rule is html.CssStyleRule &&
                 rule.selectorText == '.${_ITEM_CSS_CLASS}';
        });
        _outlineItemCssRules.addAll(rules);
      });
  
    }
  
    Stream<OutlineItem> get onChildSelected => _childSelectedController.stream;
  