anchor.diff:              _exceptionHandler(e, s);
             }
             _domWriteHead = _domWriteHead._next;
  +          if (_domWriteHead == null) _stats.domWriteEnd();
           }
           _domWriteTail = null;
           if (runObservers) {
             runObservers = false;
  -          observeGroup.detectChanges(exceptionHandler:_exceptionHandler);
  -        }
  +          readOnlyGroup.detectChanges(exceptionHandler:_exceptionHandler);
  +        }
  +        if (_domReadHead != null) _stats.domWriteStart();
           while (_domReadHead != null) {
             try {
               _domReadHead.fn();
  
positive.code:   }
  
    void digestStart() {
      _digestStopwatchReset();
      _digestLoopNo = 0;
    }
  
negative.code:     var child = new Scope(childContext, rootScope, this,
                            _readWriteGroup.newGroup(childContext),
                            _readOnlyGroup.newGroup(childContext),
                           '$id:${_childScopeNextId++}',
                           _stats);
  
      var prev = _childTail;
      child._prev = prev;
  