Repository: flutter
Issue: [a11y][VoiceOver/Talkback] Dismissable ModalBarrier is not announced as a button
Labels: framework,a: accessibility,has reproducible steps,P3,found in release: 3.24,team-accessibility,triaged-accessibility,found in release: 3.27

### Steps to reproduce

1. Have an app with a popupMenu
2. Enable VoiceOver / Talkback
3. Swipe until you get Dismiss Menu semantic

### Expected results

Element should be labelled as button by VoiceOver/Talkback as it has an onTap action.

### Actual results

Element is not labelled as button

### Code sample

<details open><summary>Code sample</summary>

```dart
import 'package:flutter/material.dart';
import 'package:flutter_localizations/flutter_localizations.dart';

void main() {
  runApp(MaterialApp(
    title: 'Flutter Demo',
    localizationsDelegates: const [
      GlobalMaterialLocalizations.delegate,
      GlobalWidgetsLocalizations.delegate,
      GlobalCupertinoLocalizations.delegate,
    ],
    debugShowCheckedModeBanner: false,
    supportedLocales: <Locale>[
      Locale('en', 'US'), // English
    ],
    home: MyApp(),
  ));
}

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: TextButton(
          child: Text('Hello, World!'),
          onPressed: () {
            showMenu<String>(
              shape: const RoundedRectangleBorder(borderRadius: BorderRadius.all(Radius.circular(16.0))),
              context: context,
              items: [PopupMenuItem(child: Text('Menu1')), PopupMenuItem(child: Text('Menu2'))],
              position: RelativeRect.fromLTRB(
                0,
                0,
                0,
                0,
              ),
            );
          },
        ),
      ),
    );
  }
}
```

</details>


### Screenshots or Video

<details open>
<summary>Screenshots / Video demonstration</summary>

https://github.com/user-attachments/assets/7c9983ab-13eb-4886-9733-9209744b3474

<img width="1115" alt="Capture d’écran 2024-11-05 à 13 55 01" src="https://github.com/user-attachments/assets/3def05d3-35d8-4401-b9dc-514881568877">


</details>


### Logs

_No response_

### Flutter Doctor output

<details open><summary>Doctor output</summary>

```console
[✓] Flutter (Channel stable, 3.19.3, on macOS 14.6.1 23G93 darwin-arm64, locale fr-FR)
    • Flutter version 3.19.3 on channel stable at /Users/jeremy_bastien/fvm/versions/3.19.3
    • Upstream repository https://github.com/flutter/flutter.git
    • Framework revision ba39319843 (8 months ago), 2024-03-07 15:22:21 -0600
    • Engine revision 2e4ba9c6fb
    • Dart version 3.3.1
    • DevTools version 2.31.1

[✓] Android toolchain - develop for Android devices (Android SDK version 34.0.0)
    • Android SDK at /Users/jeremy_bastien/Library/Android/sdk
    • Platform android-34, build-tools 34.0.0
    • ANDROID_HOME = /Users/jeremy_bastien/Library/Android/sdk
    • Java binary at: /Applications/Android Studio.app/Contents/jbr/Contents/Home/bin/java
    • Java version OpenJDK Runtime Environment (build 17.0.11+0-17.0.11b1207.24-11852314)
    • All Android licenses accepted.

[✓] Xcode - develop for iOS and macOS (Xcode 15.4)
    • Xcode at /Applications/Xcode 15/Xcode.app/Contents/Developer
    • Build 15F31d
    • CocoaPods version 1.15.2

[✓] Chrome - develop for the web
    • Chrome at /Applications/Google Chrome.app/Contents/MacOS/Google Chrome

[✓] Android Studio (version 2024.1)
    • Android Studio at /Applications/Android Studio.app/Contents
    • Flutter plugin can be installed from:
      🔨 https://plugins.jetbrains.com/plugin/9212-flutter
    • Dart plugin can be installed from:
      🔨 https://plugins.jetbrains.com/plugin/6351-dart
    • android-studio-dir = /Applications/Android Studio.app
    • Java version OpenJDK Runtime Environment (build 17.0.11+0-17.0.11b1207.24-11852314)

[✓] IntelliJ IDEA Ultimate Edition (version 2024.2.4)
    • IntelliJ at /Applications/IntelliJ IDEA.app
    • Flutter plugin can be installed from:
      🔨 https://plugins.jetbrains.com/plugin/9212-flutter
    • Dart plugin can be installed from:
      🔨 https://plugins.jetbrains.com/plugin/6351-dart

[✓] IntelliJ IDEA Ultimate Edition (version 2024.1.5)
    • IntelliJ at /Users/jeremy_bastien/Applications/IntelliJ IDEA Ultimate.app
    • Flutter plugin version 81.0.2
    • Dart plugin version 241.18968.26

[✓] Connected device (2 available)
    • macOS (desktop)                  • macos                     • darwin-arm64   • macOS 14.6.1 23G93 darwin-arm64
    • Chrome (web)                     • chrome                    • web-javascript • Google Chrome 130.0.6723.92

[✓] Network resources
    • All expected network resources are available.
```

</details>