anchor.diff:    }
   }
   
  +@override
   class ChatMessage extends StatelessWidget {
  -  ChatMessage({this.text, this.animationController});
  -  final String text;
  -  final AnimationController animationController;
  +
  +  ChatMessage({this.snapshot, this.animation});
  +  final DataSnapshot snapshot;
  +  final Animation animation;
  +
     @override
     Widget build(BuildContext context) {
       return new SizeTransition(
         sizeFactor: new CurvedAnimation(
  -        parent: animationController,
  -        curve: Curves.easeOut
  +        parent: animation, curve: Curves.easeOut
         ),
         axisAlignment: 0.0,
         child: new Container(
  
positive.code: import 'dart:async';
  import 'package:firebase_analytics/firebase_analytics.dart';
  import 'package:firebase_auth/firebase_auth.dart';
  
  final googleSignIn = new GoogleSignIn();
  final analytics = new FirebaseAnalytics();
  
negative.code:       body: new Container(
          child: new Column(
            children: <Widget>[
              new Flexible(
                child: new FirebaseAnimatedList(
                  query: reference,
                  sort: (a, b) => b.key.compareTo(a.key),
                  padding: new EdgeInsets.all(8.0),
                  reverse: true,
                  itemBuilder: (_, DataSnapshot snapshot, Animation<double> animation) {
                    return new ChatMessage(
                        snapshot: snapshot,
                        animation: animation
                    );
                  },
                ),
              ),
            new Divider(height: 1.0),
            new Container(
              decoration: new BoxDecoration(
  