M3 DatePicker landscape header text style is now TextTheme.headlineSmall

Reland: Updates `flutter/test/material` to no longer use `TestWindow`

This reverts commit b2fc5f97.

Updates `flutter/test/material` to no longer use `TestWindow`

Fix how tests count open SemanticsHandles

This reverts commit d2788080.

* Check whether slider is mounted before interaction, no-op if unmounted (#113556)

* Check whether slider is unmounted before interaction

* Update slider.dart

* Update Slider

* Add test

* Update slider_test.dart

* Update packages/flutter/test/material/slider_test.dart
Co-authored-by: Taha Tesser <tessertaha@gmail.com>
Co-authored-by: Taha Tesser <tessertaha@gmail.com>

* exposed tooltip longPress action when available

* updated tooltip test

* updated date picker test

---------
Co-authored-by: Mingyu <lyming90@gmail.com>
Co-authored-by: Taha Tesser <tessertaha@gmail.com>
Co-authored-by: Harper Liu <harperl0818@gmail.com>

* Revert "Exposed tooltip longPress action when available (#117338)"

This reverts commit 38e3930f.

* Revert "fixes android_semantics_integration_test to expect long press for tootip"

* Exposed tooltip longPress action when available (Trigger mode is long press)

* Date picker special labeling for currentDate with localization and tests.

* Updated CalendarDatePicker semantics test

* removed recursive import

* changed labeling for current date to be less verbose

* init

* upper case only when material 2

* fix test

* fix test

* fix tests again

* Add all tests

* analyze"

* fix stepper

This reverts commit 5fd259be.

Added the ability to bring up the date picker dialogs in calendar or text input only modes that don't allow the user to switch. (#76343)

Date Picker restructuring. Moved files out of 'pickers' and merged several of the non-public implementation files into date_picker.dart.

Date Picker jumps back to initialDatePickerMode after day selection.

Migrate Material framework tests to null safety.

Updated references to the old button classes to the new ones in comments and documentation for tests in the material and cupertino libraries. (#62164)