BodyHandle body_handle(JSObject *obj) {
  MOZ_ASSERT(is_instance(obj));
  return BodyHandle{static_cast<uint32_t>(JS::GetReservedSlot(obj, Slots::Body).toInt32())};
}
BodyHandle body_handle(JSObject *obj) {
  MOZ_ASSERT(is_instance(obj));
  return BodyHandle{static_cast<uint32_t>(JS::GetReservedSlot(obj, Slots::Body).toInt32())};
}