int insertRule(String rule, [ int index ])

Source

int insertRule(String rule, [int index]) {
  if (index != null) {
    return _blink.BlinkCSSStyleSheet.instance
        .insertRule_Callback_2_(this, rule, index);
  }
  return _blink.BlinkCSSStyleSheet.instance
      .insertRule_Callback_1_(this, rule);
}