anchor.diff:  
   import 'dart:async';
   import 'dart:collection';
  +import 'dart:mirrors';
   import 'dart:sky' as sky;
   import 'reflect.dart' as reflect;
   import 'layout.dart';
  
positive.code:     } else {
        _traceSync(_SyncOperation.STATELESS, node._key);
      }
      node._sync(oldNode, host, insertBefore);
      if (oldNode != null)
        oldNode._defunct = true;
  
  
negative.code:     assert(!_debugHasDuplicateIds());
    }
  
    void insert(RenderNodeWrapper child, dynamic slot) {
      assert(slot == null || slot is RenderCSS);
      _root.add(child._root, before: slot);
    }
  
    void _remove() {
      assert(children != null);
      for (var child in children) {
  