anchor.diff:     * This doesn't work in some browsers (Opera).
      */
     void _beforeUnload(unused) {
  -    document.cookie = '${PREFIX}=s=${new Date.now().millisecondsSinceEpoch}&'
  -         'r=${encodeUriComponent(window.location.toString())}; path=/';
  +    document.cookie = '${PREFIX}=s=${new DateTime.now().millisecondsSinceEpoch}&'
  +         'r=${Uri.encodeComponent(window.location.toString())}; path=/';
     }
   
     /**
  
positive.code:       return;
      }
      if (markTime == null) {
        markTime = new Date.now().millisecondsSinceEpoch;
      } else if (markTime is! int) {
        try {
          // Make sure the time is a number.
  
negative.code:       startTime = _findStartCookie();
        if (startTime == null) {
          // fall back to now
          startTime = new DateTime.now().millisecondsSinceEpoch;
        }
      }
      mark(START_TIME, startTime);
  