Firestore & documents ＆ updataDataに斜線が入り、実行できません。どうしたらよろしいでしょうか

Question

Widget _buildBody(BuildContext context) {

return StreamBuilder<QuerySnapshot>(
    stream: Firestore.instance.collection('baby').snapshots(), 
    builder: (context, snapshot) {
      if (!snapshot.hasData) return LinearProgressIndicator();

      return _buildList(context, snapshot.data.documents);

},
);
}

---

Widget _buildListItem(BuildContext context, DocumentSnapshot data) {

final record = Record.fromSnapshot(data);
return Padding(
  key: ValueKey(record.name),
  padding: const EdgeInsets.symmetric(horizontal: 16.0, vertical: 8.0),
  child: Container(
    decoration: BoxDecoration(
      border: Border.all(color: Colors.grey),
      borderRadius: BorderRadius.circular(5.0),
    ),
    child: ListTile(
      title: Text(record.name),
      trailing: Text(record.votes.toString()),

    onTap: () => record.reference.updateData({'votes' : FieldValue.increment(1)}),
    ),
  ),
);

}
}