void scrollBy([options_OR_x, y, Map scrollOptions ])

Source 

void scrollBy([options_OR_x, y, Map scrollOptions]) {
  if (options_OR_x == null && y == null && scrollOptions == null) {
    _blink.BlinkWindow.instance.scrollBy_Callback_0_(this);
    return;
  }
  if ((options_OR_x is Map) && y == null && scrollOptions == null) {
    _blink.BlinkWindow.instance.scrollBy_Callback_1_(this, options_OR_x);
    return;
  }
  if ((y is num) && (options_OR_x is num) && scrollOptions == null) {
    _blink.BlinkWindow.instance.scrollBy_Callback_2_(this, options_OR_x, y);
    return;
  }
  if ((y is int) && (options_OR_x is int) && scrollOptions == null) {
    _blink.BlinkWindow.instance.scrollBy_Callback_2_(this, options_OR_x, y);
    return;
  }
  if ((scrollOptions is Map) && (y is int) && (options_OR_x is int)) {
    _blink.BlinkWindow.instance.scrollBy_Callback_3_(
        this, options_OR_x, y, convertDartToNative_Dictionary(scrollOptions));
    return;
  }
  throw new ArgumentError("Incorrect number or type of arguments");
}