JSObject *body_stream(JSObject *obj) {
  MOZ_ASSERT(is_instance(obj));
  return JS::GetReservedSlot(obj, Slots::BodyStream).toObjectOrNull();
}
JSObject *body_stream(JSObject *obj) {
  MOZ_ASSERT(is_instance(obj));
  return JS::GetReservedSlot(obj, Slots::BodyStream).toObjectOrNull();
}