Upgrading samples to flutter_lints, part 1 of n (#804)

infinite_list/lib/main.dart

@@ -30,7 +30,7 @@ class MyHomePage extends StatelessWidget {
   Widget build(BuildContext context) {
     return Scaffold(
       appBar: AppBar(
-        title: Text('Infinite List Sample'),
+        title: const Text('Infinite List Sample'),
       ),
       body: Selector<Catalog, int?>(
         // Selector is a widget from package:provider. It allows us to listen
@@ -54,7 +54,7 @@ class MyHomePage extends StatelessWidget {
             var item = catalog.getByIndex(index);
 
             if (item.isLoading) {
-              return LoadingItemTile();
+              return const LoadingItemTile();
             }
 
             return ItemTile(item: item);

infinite_list/lib/src/item_tile.dart

@@ -11,7 +11,7 @@ import 'api/item.dart';
 class ItemTile extends StatelessWidget {
   final Item item;
 
-  ItemTile({required this.item, Key? key}) : super(key: key);
+  const ItemTile({required this.item, Key? key}) : super(key: key);
 
   @override
   Widget build(BuildContext context) {
@@ -41,12 +41,12 @@ class LoadingItemTile extends StatelessWidget {
     return Padding(
       padding: const EdgeInsets.all(8.0),
       child: ListTile(
-        leading: AspectRatio(
+        leading: const AspectRatio(
           aspectRatio: 1,
           child: Placeholder(),
         ),
         title: Text('...', style: Theme.of(context).textTheme.headline6),
-        trailing: Text('\$ ...'),
+        trailing: const Text('\$ ...'),
       ),
     );
   }