double timeDilation

Slows down animations by this factor to help in development.

Source 

double get timeDilation => _timeDilation;
void timeDilation=(double value)

Setting the time dilation automatically calls SchedulerBinding.resetEpoch to ensure that time stamps seen by consumers of the scheduler binding are always increasing.

Source 

set timeDilation(double value) {
  assert(value > 0.0);
  if (_timeDilation == value)
    return;
  // We need to resetEpoch first so that we capture start of the epoch with the
  // current time dilation.
  SchedulerBinding.instance?.resetEpoch();
  _timeDilation = value;
}