Repository: flutter
Issue: [iOS] CupertinoAlertDialog has a wrong color/shade above platform-views
Labels: c: regression,platform-ios,framework,engine,f: cupertino,a: platform-views,has reproducible steps,P2,team-ios,triaged-ios,found in release: 3.13,found in release: 3.17

### Is there an existing issue for this?

- [X] I have searched the [existing issues](https://github.com/flutter/flutter/issues)
- [X] I have read the [guide to filing a bug](https://flutter.dev/docs/resources/bug-reports)

### Steps to reproduce

1. Run the provided code.
2. Click the button to show CupertinoAlertDialog.

### Expected results

CupertinoAlertDialog should look the same as without WebView


### Actual results

Cupertino has a different color above WebView


### Code sample

<details><summary>Code sample</summary>

```dart
import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
import 'package:webview_flutter/webview_flutter.dart';

void main() {
  runApp(const ExampleApp());
}

class ExampleApp extends StatelessWidget {
  const ExampleApp({super.key});

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'WebView CupertinoAlertDialog',
      theme: ThemeData(),
      home: const MyHomePage(),
    );
  }
}

class MyHomePage extends StatelessWidget {
  const MyHomePage({super.key});

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      backgroundColor: Colors.white,
      appBar: AppBar(
        title: const Text('WebView CupertinoAlertDialog'),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            SizedBox(
              height: 100,
              child: WebViewWidget(
                controller: WebViewController()
                  ..loadRequest(
                    Uri.parse('https://flutter.dev'),
                  ),
              ),
            ),
            ElevatedButton(
                onPressed: () {
                  showDialog<void>(
                    context: context,
                    builder: (BuildContext context) {
                      return CupertinoAlertDialog(
                        title: const Text('Title'),
                        content: const Text('Content'),
                        actions: <Widget>[
                          TextButton(
                            style: TextButton.styleFrom(
                              textStyle: Theme.of(context).textTheme.labelLarge,
                            ),
                            child: const Text('Close'),
                            onPressed: () {
                              Navigator.of(context).pop();
                            },
                          ),
                        ],
                      );
                    },
                  );
                },
                child: const Text("Show CupertinoAlertDialog"))
          ],
        ),
      ),
    );
  }
}
```
</details>

### Screenshots or Video

<details>
<summary>Screenshots / Video demonstration</summary>

Actual  CupertinoAlertDialog  result screenshot:
![Simulator Screenshot - iPhone 15 - 2023-11-14 at 23 37 16](https://github.com/flutter/flutter/assets/48891926/918b7641-a35f-4e72-9a2e-97fa87cb3880)

Expected CupertinoAlertDialog result screenshot:
![Simulator Screenshot - iPhone 15 - 2023-11-14 at 23 39 46](https://github.com/flutter/flutter/assets/48891926/97760c13-9094-4a82-95c9-9c23a8427c5c)




</details>


### Flutter Doctor output

<details><summary>Doctor output</summary>

```console
Doctor summary (to see all details, run flutter doctor -v):
[✓] Flutter (Channel stable, 3.13.9, on macOS 14.0 23A344 darwin-x64, locale pl-PL)
[✓] Android toolchain - develop for Android devices (Android SDK version 33.0.0)
[✓] Xcode - develop for iOS and macOS (Xcode 15.0.1)
[✓] Chrome - develop for the web
[✓] Android Studio (version 2022.3)
[✓] Android Studio (version 2022.3)
[✓] VS Code (version 1.84.2)
[✓] Connected device (3 available)
[✓] Network resources

• No issues found!
```

</details>