Implement switch expressions in examples/ and animation/ (#139882)

Thanks so much for approving the previous PR (#139048) a couple weeks ago!

This one is the same, except it's covering files in `examples/` and `packages/flutter/lib/src/animation/`.

(solving issue #136139)

examples/api/lib/material/color_scheme/dynamic_content_color.0.dart

@@ -366,12 +366,10 @@ class ColorChip extends StatelessWidget {
 
   static Color contrastColor(Color color) {
     final Brightness brightness = ThemeData.estimateBrightnessForColor(color);
-    switch (brightness) {
-      case Brightness.dark:
-        return Colors.white;
-      case Brightness.light:
-        return Colors.black;
-    }
+    return switch (brightness) {
+      Brightness.dark  => Colors.white,
+      Brightness.light => Colors.black,
+    };
   }
 
   @override

examples/api/lib/widgets/slotted_render_object_widget/slotted_multi_child_render_object_widget_mixin.0.dart

@@ -33,12 +33,10 @@ class Diagonal extends SlottedMultiChildRenderObjectWidget<DiagonalSlot, RenderB
 
   @override
   Widget? childForSlot(DiagonalSlot slot) {
-    switch (slot) {
-      case DiagonalSlot.topLeft:
-        return topLeft;
-      case DiagonalSlot.bottomRight:
-        return bottomRight;
-    }
+    return switch (slot) {
+      DiagonalSlot.topLeft     => topLeft,
+      DiagonalSlot.bottomRight => bottomRight,
+    };
   }
 
   // The [createRenderObject] and [updateRenderObject] methods configure the

examples/layers/services/isolate.dart

@@ -272,14 +272,11 @@ class IsolateExampleState extends State<StatefulWidget> with SingleTickerProvide
   }
 
   String _getStatus(CalculationState state) {
-    switch (state) {
-      case CalculationState.loading:
-        return 'Loading...';
-      case CalculationState.calculating:
-        return 'In Progress';
-      case CalculationState.idle:
-        return 'Idle';
-    }
+    return switch (state) {
+      CalculationState.loading     => 'Loading...',
+      CalculationState.calculating => 'In Progress',
+      CalculationState.idle        => 'Idle',
+    };
   }
 
   void _updateState(String result, double progress) {

examples/platform_view/lib/main.dart

@@ -48,20 +48,14 @@ class _MyHomePageState extends State<MyHomePage> {
   }
 
   static Widget get _buttonText {
-    switch (defaultTargetPlatform) {
-      case TargetPlatform.android:
-        return const Text('Continue in Android view');
-      case TargetPlatform.iOS:
-        return const Text('Continue in iOS view');
-      case TargetPlatform.windows:
-        return const Text('Continue in Windows view');
-      case TargetPlatform.macOS:
-        return const Text('Continue in macOS view');
-      case TargetPlatform.linux:
-        return const Text('Continue in Linux view');
-      case TargetPlatform.fuchsia:
-        throw UnimplementedError('Platform not yet implemented');
-    }
+    return switch (defaultTargetPlatform) {
+      TargetPlatform.android => const Text('Continue in Android view'),
+      TargetPlatform.iOS     => const Text('Continue in iOS view'),
+      TargetPlatform.windows => const Text('Continue in Windows view'),
+      TargetPlatform.macOS   => const Text('Continue in macOS view'),
+      TargetPlatform.linux   => const Text('Continue in Linux view'),
+      TargetPlatform.fuchsia => throw UnimplementedError('Platform not yet implemented'),
+    };
   }
 
   Future<void> _launchPlatformCount() async {

packages/flutter/lib/src/animation/animation.dart

@@ -269,16 +269,12 @@ abstract class Animation<T> extends Listenable implements ValueListenable<T> {
   /// * "&#x23ED;": [AnimationStatus.completed] ([value] == 1.0)
   /// * "&#x23EE;": [AnimationStatus.dismissed] ([value] == 0.0)
   String toStringDetails() {
-    switch (status) {
-      case AnimationStatus.forward:
-        return '\u25B6'; // >
-      case AnimationStatus.reverse:
-        return '\u25C0'; // <
-      case AnimationStatus.completed:
-        return '\u23ED'; // >>|
-      case AnimationStatus.dismissed:
-        return '\u23EE'; // |<<
-    }
+    return switch (status) {
+      AnimationStatus.forward   => '\u25B6', // >
+      AnimationStatus.reverse   => '\u25C0', // <
+      AnimationStatus.completed => '\u23ED', // >>|
+      AnimationStatus.dismissed => '\u23EE', // |<<
+    };
   }
 }
 

packages/flutter/lib/src/animation/animations.dart

@@ -307,12 +307,12 @@ class ReverseAnimation extends Animation<double>
   double get value => 1.0 - parent.value;
 
   AnimationStatus _reverseStatus(AnimationStatus status) {
-    switch (status) {
-      case AnimationStatus.forward: return AnimationStatus.reverse;
-      case AnimationStatus.reverse: return AnimationStatus.forward;
-      case AnimationStatus.completed: return AnimationStatus.dismissed;
-      case AnimationStatus.dismissed: return AnimationStatus.completed;
-    }
+    return switch (status) {
+      AnimationStatus.forward   => AnimationStatus.reverse,
+      AnimationStatus.reverse   => AnimationStatus.forward,
+      AnimationStatus.completed => AnimationStatus.dismissed,
+      AnimationStatus.dismissed => AnimationStatus.completed,
+    };
   }
 
   @override