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">

dev/tools/gen_defaults/generated/used_tokens.csv

@@ -423,6 +423,7 @@ md.comp.navigation-drawer.active-indicator.color,
 md.comp.navigation-drawer.active-indicator.height,
 md.comp.navigation-drawer.active-indicator.shape,
 md.comp.navigation-drawer.active-indicator.width,
+md.comp.navigation-drawer.active.icon.color,
 md.comp.navigation-drawer.active.label-text.color,
 md.comp.navigation-drawer.container.color,
 md.comp.navigation-drawer.container.surface-tint-layer.color,

dev/tools/gen_defaults/lib/navigation_drawer_template.dart

@@ -43,7 +43,7 @@ class _${blockName}DefaultsM3 extends NavigationDrawerThemeData {
       return IconThemeData(
         size: ${getToken("md.comp.navigation-drawer.icon.size")},
         color: states.contains(MaterialState.selected)
-            ? ${componentColor("md.comp.navigation-drawer.active.icon.")}
+            ? ${componentColor("md.comp.navigation-drawer.active.icon")}
             : ${componentColor("md.comp.navigation-drawer.inactive.icon")},
       );
     });

packages/flutter/lib/src/material/navigation_drawer.dart

@@ -218,7 +218,7 @@ class NavigationDrawerDestination extends StatelessWidget {
   ///
   /// The icon will use [NavigationDrawerThemeData.iconTheme] with
   /// [MaterialState.selected]. If this is null, the default [IconThemeData]
-  /// would use a size of 24.0 and [ColorScheme.onSurfaceVariant].
+  /// would use a size of 24.0 and [ColorScheme.onSecondaryContainer].
   final Widget? selectedIcon;
 
   /// The text label that appears on the right of the icon
@@ -702,7 +702,7 @@ class _NavigationDrawerDefaultsM3 extends NavigationDrawerThemeData {
       return IconThemeData(
         size: 24.0,
         color: states.contains(MaterialState.selected)
-            ? null
+            ? _colors.onSecondaryContainer
             : _colors.onSurfaceVariant,
       );
     });

packages/flutter/test/material/navigation_drawer_test.dart

@@ -115,7 +115,7 @@ void main() {
   });
 
   testWidgets(
-      'M3 NavigationDrawer uses proper defaults when no parameters are given',
+    'NavigationDrawer uses proper defaults when no parameters are given',
       (WidgetTester tester) async {
     final GlobalKey<ScaffoldState> scaffoldKey = GlobalKey<ScaffoldState>();
     final ThemeData theme = ThemeData(useMaterial3: true);
@@ -125,13 +125,13 @@ void main() {
         NavigationDrawer(
           children: <Widget>[
             Text('Headline', style: theme.textTheme.bodyLarge),
-            NavigationDrawerDestination(
-              icon: Icon(Icons.ac_unit, color: theme.iconTheme.color),
-              label: Text('AC', style: theme.textTheme.bodySmall),
+            const NavigationDrawerDestination(
+              icon: Icon(Icons.ac_unit),
+              label: Text('AC'),
             ),
-            NavigationDrawerDestination(
-              icon: Icon(Icons.access_alarm, color: theme.iconTheme.color),
-              label: Text('Alarm', style: theme.textTheme.bodySmall),
+            const NavigationDrawerDestination(
+              icon: Icon(Icons.access_alarm),
+              label: Text('Alarm'),
             ),
           ],
           onDestinationSelected: (int i) {},
@@ -142,11 +142,25 @@ void main() {
     scaffoldKey.currentState!.openDrawer();
     await tester.pump(const Duration(seconds: 1));
 
+    // Test drawer Material.
     expect(_getMaterial(tester).color, theme.colorScheme.surface);
     expect(_getMaterial(tester).surfaceTintColor, theme.colorScheme.surfaceTint);
+    expect(_getMaterial(tester).shadowColor, Colors.transparent);
     expect(_getMaterial(tester).elevation, 1);
+    // Test indicator decoration.
     expect(_getIndicatorDecoration(tester)?.color, theme.colorScheme.secondaryContainer);
     expect(_getIndicatorDecoration(tester)?.shape, const StadiumBorder());
+    // Test selected and unselected icon colors.
+    expect(_iconStyle(tester, Icons.ac_unit)?.color, theme.colorScheme.onSecondaryContainer);
+    expect(_iconStyle(tester, Icons.access_alarm)?.color, theme.colorScheme.onSurfaceVariant);
+    // Test selected and unselected label colors.
+    expect(_labelStyle(tester, 'AC')?.color, theme.colorScheme.onSecondaryContainer);
+    expect(_labelStyle(tester, 'Alarm')?.color, theme.colorScheme.onSurfaceVariant);
+    // Test that the icon and label are the correct size.
+    RenderBox iconBox = tester.renderObject(find.byIcon(Icons.ac_unit));
+    expect(iconBox.size, const Size(24.0, 24.0));
+    iconBox = tester.renderObject(find.byIcon(Icons.access_alarm));
+    expect(iconBox.size, const Size(24.0, 24.0));
   });
 
   testWidgets('Navigation drawer is scrollable', (WidgetTester tester) async {
@@ -418,6 +432,20 @@ ShapeDecoration? _getIndicatorDecoration(WidgetTester tester) {
       .decoration as ShapeDecoration?;
 }
 
+TextStyle? _iconStyle(WidgetTester tester, IconData icon) {
+  final RichText iconRichText = tester.widget<RichText>(
+    find.descendant(of: find.byIcon(icon), matching: find.byType(RichText)),
+  );
+  return iconRichText.text.style;
+}
+
+TextStyle? _labelStyle(WidgetTester tester, String label) {
+  final RichText labelRichText = tester.widget<RichText>(
+    find.descendant(of: find.text(label), matching: find.byType(RichText)),
+  );
+  return labelRichText.text.style;
+}
+
 void widgetSetup(WidgetTester tester, double viewWidth, {double viewHeight = 1000}) {
   tester.view.devicePixelRatio = 2;
   final double dpi = tester.view.devicePixelRatio;