anchor.diff:  
   
     _Watch _digestComputeLastDirty() {
  +    int watcherCount = 0;
  +    int scopeCount = 0;
       Scope scope = this;
       do {
  -      for (_Watch watch = scope._watchers.head; watch != null; watch = watch.next) {
  +      _WatchList watchers = scope._watchers;
  +      watcherCount += watchers.length;
  +      scopeCount++;
  +      for (_Watch watch = watchers.head; watch != null; watch = watch.next) {
           var last = watch.last;
           var value = watch.get(scope);
           if (!_identical(value, last)) {
  
positive.code:       assert(_perf.stopTimer(timerId) != false);
  
        if (lastDirtyWatch == null) {
          _digestUpdatePerfCounters();
          _digestHandleQueue('ng.outerAsync', _outerAsyncQueue);
          return;
        }
  
negative.code:     assert(_perf.stopTimer(timerId) != false);
  
      if (lastDirtyWatch == null) {
        _digestHandleQueue('ng.outerAsync', _outerAsyncQueue);
        return;
      }
  