Taha Tesser 7cef966147
Fix NavigationDrawer selected item has wrong icon color (#129625)
fixes [NavigationDrawer selected item has wrong icon color [Material3 spec]](https://github.com/flutter/flutter/issues/129572)

### Description
This PR fixes a mistake in the `NavigationDrawer` defaults, where generated token value returns a `null`. 
This issue can be detected when you want to customize the selected icon color for `NavigationDrawerDestination` using a custom color scheme.

### Code sample

<details> 
<summary>expanded to view the code sample</summary> 

```dart
import 'package:flutter/material.dart';

void main() => runApp(const MyApp());

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      themeMode: ThemeMode.light,
      theme: ThemeData(
        colorScheme: ColorScheme.fromSeed(seedColor: Colors.blue).copyWith(
          onSecondaryContainer: Colors.red,
        ),
        useMaterial3: true,
      ),
      home: const Example(),
    );
  }
}

class Example extends StatelessWidget {
  const Example({super.key});

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('NavigationDrawer Sample'),
      ),
      drawer: const NavigationDrawer(
        children: <Widget>[
          NavigationDrawerDestination(
            icon: Icon(Icons.favorite_outline_rounded),
            label: Text('Favorite'),
            selectedIcon: Icon(Icons.favorite_rounded),
          ),
          NavigationDrawerDestination(
            icon: Icon(Icons.favorite_outline_rounded),
            label: Text('Favorite'),
          ),
        ],
      ),
    );
  }
}
``` 
	
</details>

### Before
 
<img width="1053" alt="Screenshot 2023-06-27 at 13 24 38" src="https://github.com/flutter/flutter/assets/48603081/18c13a73-688f-4586-bb60-bddef45d173f">

### After

<img width="1053" alt="Screenshot 2023-06-27 at 13 24 25" src="https://github.com/flutter/flutter/assets/48603081/8a1427c6-517f-424a-b0bd-24bad7c5fbb0">
2023-06-30 08:58:14 +00:00
..
2023-06-28 14:07:50 -07:00
2023-06-21 21:37:00 +00:00
2023-06-28 17:16:19 -07:00
2022-12-20 00:46:14 +00:00

This directory contains tools and resources that the Flutter team uses during the development of the framework. The tools in this directory should not be necessary for developing Flutter applications, though of course, they may be interesting if you are curious.

The tests in this directory are run in the framework_tests_misc-* shards.