JSObject *backing_map(JSObject *self) {
  MOZ_ASSERT(is_instance(self));
  return &JS::GetReservedSlot(self, Slots::BackingMap).toObject();
}
JSObject *backing_map(JSObject *self) {
  MOZ_ASSERT(is_instance(self));
  return &JS::GetReservedSlot(self, Slots::BackingMap).toObject();
}