addCubicBezierCurveTo method
Implementation
void addCubicBezierCurveTo(Vector3 handle1, Vector3 handle2, Vector3 anchor) {
  throwErrorIfNoPoints('addCubicBezierCurveTo');
  if (hasNewPathStarted()) {
    appendPoints([handle1, handle2, anchor]);
  } else {
    appendPoints([getLastPoint(), handle1, handle2, anchor]);
  }
}