void setPosition(Node node, [ int offset ])

Source 

void setPosition(Node node, [int offset]) {
  if (offset != null) {
    _blink.BlinkSelection.instance.setPosition_Callback_2_(this, node, offset);
    return;
  }
  _blink.BlinkSelection.instance.setPosition_Callback_1_(this, node);
  return;
}