anchor.diff:    }
   
     dynamic runBinary(Zone zone, f(arg1, arg2), arg1, arg2) {
  -    _CustomizedZone parent = _degelationTarget;
  +    _BaseZone parent = _degelationTarget;
       while (parent._specification.runBinary == null) {
         parent = parent.parent;
       }
  
positive.code:   }
  
    Timer createTimer(Zone zone, Duration duration, void f()) {
      _CustomizedZone parent = _degelationTarget;
      while (parent._specification.createTimer == null) {
        parent = parent.parent;
      }
  
negative.code: }
  
  class _ZoneDelegate implements ZoneDelegate {
    final _BaseZone _degelationTarget;
  
    Zone get _zone => _degelationTarget;
  
    const _ZoneDelegate(this._degelationTarget);
  
    dynamic handleUncaughtError(Zone zone, error, StackTrace stackTrace) {
      _BaseZone parent = _degelationTarget;
      while (parent._specification.handleUncaughtError == null) {
        parent = parent.parent;
      }
  