Graphics new method 'drawPolygon'

/**
 * Draw Polygon
 * @param {[x, y][]} posList Position List
 */
createjs.Graphics.prototype.drawPolygon = function (...posList) {
  const copyPosList = [...posList];
  if (copyPosList.length === 0) return this;
  const firstPos = copyPosList.splice(0, 1)[0];
  let chain = this.moveTo(firstPos[0], firstPos[1]);
  for (const pos of copyPosList) chain = chain.lineTo(pos[0], pos[1]);
  return chain.lineTo(firstPos[0], firstPos[1]);
};