anchor.diff:    }
   
     void flush() {
  +    _stats.flushStart();
       _transitionState(null, STATE_FLUSH);
  -    var observeGroup = this._readOnlyGroup as RootWatchGroup;
  +    RootWatchGroup readOnlyGroup = this._readOnlyGroup as RootWatchGroup;
       bool runObservers = true;
       try {
         do {
  +        if (_domWriteHead != null) _stats.domWriteStart();
           while (_domWriteHead != null) {
             try {
               _domWriteHead.fn();
  
positive.code:   bool get hasOwnStreams => _streams != null  && _streams._scope == this;
  
    Scope(Object this.context, this.rootScope, this._parentScope,
          this._readWriteGroup, this._readOnlyGroup, this.id);
  
    /**
     * Use [watch] to set up a watch in the [apply] cycle.
  
negative.code:     var child = new Scope(childContext, rootScope, this,
                            _readWriteGroup.newGroup(childContext),
                            _readOnlyGroup.newGroup(childContext),
                           '$id:${_childScopeNextId++}',
                           _stats);
  
      var prev = _childTail;
      child._prev = prev;
  