Repository: flutter
Issue: [Desktop][a11y] Date selection from DatePicker (Calendar Control) not working when Voiceover is enabled
Labels: framework,f: material design,a: accessibility,platform-mac,a: desktop,has reproducible steps,P2,found in release: 3.7,found in release: 3.9,team-macos,triaged-macos

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When Voiceover is turned ON and the user launches DatePicker, the user is unable to navigate between calendar dates. This happens only when the starting dates (1, 2, 3, 4, 5, ...) of any month are disabled in the calendar.

## Steps to Reproduce

<!-- Please include full steps to reproduce so that we can reproduce the problem. -->
1. Create a flutter starter app & remove counter code
2. Add an Elevated button in Scaffold
3. Launch DatePicker upon Elevated Button click
4. Turn ON Voiceover
5. Navigate to the Elevated Button using Voiceover commands
6. Open DatePicker by clicking Elevated Button
7. Navigate through DatePicker using Voiceover commands



1. Execute `flutter run` on the code sample <!-- (see "Code sample" section below) -->
9. ... <!-- describe steps to demonstrate bug -->
10. ... <!-- for example "Tap on X and see a crash" -->

**Expected results:** <!-- what did you want to see? -->
Even if a few dates are disabled, the user must be able to switch between calendar dates using DatePicker.

**Actual results:** <!-- what did you see? -->
The user cannot use the voiceover command to move through calendar dates while the initial dates of any month are disabled.

<details>
<summary>Code sample</summary>

```
/// Date Picker Function: [openDatePicker] function is used display calendar
  Future<DateTime?> openDatePicker({
    DateTime? initialDate,
    DateTime? firstDate,
    DateTime? lastDate,
    bool Function(DateTime)? selectableDayPredicate,
    String? helpText,
  }) {
    final DateTime localInitialDate = initialDate ?? DateTime.now();
    final DateTime localFirstDate = firstDate ?? DateTime.now();
    final DateTime localLastDate = lastDate ??
        DateTime(
            DateTime.now().year, DateTime.now().month + 6, DateTime.now().day);

    return showDatePicker(
      context: context,
      initialDatePickerMode: DatePickerMode.day,
      initialEntryMode: DatePickerEntryMode.calendarOnly,
      initialDate: localInitialDate,
      firstDate: localFirstDate,
      lastDate: localLastDate,
      locale: kIsWeb
          ? Locale(window.locale.languageCode)
          : Locale(Platform.localeName.split('_')[0]),
      helpText: helpText,
      selectableDayPredicate: selectableDayPredicate,
      builder: (context, _) {
        return Theme(
          data: Theme.of(context).copyWith(
            colorScheme: const ColorScheme.light(
              primary: Colors.black87,
              onPrimary: Colors.white,
            ),
          ),
          child: _!,
        );
      },
    );
  }
```

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```dart
```

</details>

<details>
  <summary>Logs</summary>

<!--
     Run `flutter analyze` and attach any output of that command below.
     If there are any analysis errors, try resolving them before filing this issue.
-->

```
Analyzing test-calendar-bug... 
No issues found! (ran in 1.9s)
```

<!-- Finally, paste the output of running `flutter doctor -v` here. -->

```
Doctor summary (to see all details, run flutter doctor -v):
[✓] Flutter (Channel stable, 3.7.5, on macOS 13.1 22C65 darwin-x64, locale
    en-IN)
[✓] Android toolchain - develop for Android devices (Android SDK version
    33.0.0-rc1)
[✓] Xcode - develop for iOS and macOS (Xcode 14.1)
[✓] Chrome - develop for the web
[✓] Android Studio (version 2021.3)
[✓] VS Code (version 1.75.1)
[✓] Connected device (2 available)
[✓] HTTP Host Availability

• No issues found!
```

</details>


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https://user-images.githubusercontent.com/97581635/221836485-d1f876fa-6c73-483a-9f10-43726d03adc3.mov