anchor.diff:    HtmlElement parentElement;
   
     // The depth of this row in the overall tree.
  -  int level;
  +  final int level;
   
     // Stored comparator for the sorting function.
     // Because the tree is generated lazily, this needs to be stored to
  
positive.code:     open = !open;
      if (open) {
        if (children.isEmpty) {
          children = generatorFns.map((a) => a()).toList();
          // Resort because more children were generated.
          sort(sortComparator);
        }
  
negative.code: 
    // A function that is called when this tree needs to be rendered
    // into the DOM.
    final RenderFunction renderFunction;
  
    // The actual rendered row.
    TreeTableRow rowElement;
  