void addHitRegion([Map options ])

Source 

void addHitRegion([Map options]) {
  if (options != null) {
    _blink.BlinkCanvasRenderingContext2D.instance.addHitRegion_Callback_1_(this, convertDartToNative_Dictionary(options));
    return;
  }
  _blink.BlinkCanvasRenderingContext2D.instance.addHitRegion_Callback_0_(this);
  return;
}