Remove unnecessary types (#946)

navigation_and_routing/lib/src/app.dart

@@ -68,7 +68,7 @@ class _BookstoreState extends State<Bookstore> {
             // https://github.com/flutter/flutter/issues/82053
             theme: ThemeData(
               pageTransitionsTheme: const PageTransitionsTheme(
-                builders: <TargetPlatform, PageTransitionsBuilder>{
+                builders: {
                   TargetPlatform.android: FadeUpwardsPageTransitionsBuilder(),
                   TargetPlatform.iOS: CupertinoPageTransitionsBuilder(),
                   TargetPlatform.linux: FadeUpwardsPageTransitionsBuilder(),

navigation_and_routing/lib/src/data/author.dart

@@ -7,7 +7,7 @@ import 'book.dart';
 class Author {
   final int id;
   final String name;
-  final List<Book> books = <Book>[];
+  final books = <Book>[];
 
   Author(this.id, this.name);
 }

navigation_and_routing/lib/src/screens/navigator.dart

@@ -30,9 +30,9 @@ class BookstoreNavigator extends StatefulWidget {
 
 class _BookstoreNavigatorState extends State<BookstoreNavigator> {
   final _signInKey = const ValueKey('Sign in');
-  final _scaffoldKey = const ValueKey<String>('App scaffold');
+  final _scaffoldKey = const ValueKey('App scaffold');
-  final _bookDetailsKey = const ValueKey<String>('Book details screen');
+  final _bookDetailsKey = const ValueKey('Book details screen');
-  final _authorDetailsKey = const ValueKey<String>('Author details screen');
+  final _authorDetailsKey = const ValueKey('Author details screen');
 
   @override
   Widget build(BuildContext context) {

navigation_and_routing/lib/src/screens/settings.dart

@@ -76,7 +76,7 @@ class SettingsContent extends StatelessWidget {
               builder: (context) => AlertDialog(
                 title: const Text('Alert!'),
                 content: const Text('The alert description goes here.'),
-                actions: <Widget>[
+                actions: [
                   TextButton(
                     onPressed: () => Navigator.pop(context, 'Cancel'),
                     child: const Text('Cancel'),