anchor.diff:      if ((flags & framePendingFlag) == 0) {
         return;
       }
  +    time = t;
   
       _zone.run(() {
         flags &= ~framePendingFlag;
  
positive.code:       return;
      }
  
      _zone.run(() {
        flags &= ~tickPendingFlag;
        flags |= tickRunningFlag;
  
negative.code:   }
  
    void run(fn) {
      time = html.window.performance.now();
  
      _zone.run(() {
        flags |= tickRunningFlag;
  
  