This PR is to make `InputDecorationTheme` conform to Flutter Material's
conventions for component themes:
- Added a `InputDecorationThemeData` class which defines overrides for
the defaults for `InputDecorator` properties.
- Added `InputDecorationTheme` constructor parameters:
`InputDecorationThemeData? data` and `Widget? child`. This is now the
preferred way to configure a `InputDecorationTheme`:
```dart
InputDecorationTheme(
data: InputDecorationThemeData(
filled: true,
fillColor: Colors.amber,
...
),
child: const TextField()
)
```
These two properties are made nullable to not break existing apps which
has customized `ThemeData.inputDecorationTheme`.
- Update `InputDecorationTheme` to be an `InheritedTheme` subclass.
- Changed the type of component theme defaults from
`InputDecorationTheme` to `InputDecorationThemeData`.
- Changed the `InputDecorationTheme bottomAppBarTheme` property to
`Object? bottomAppBarTheme` in `ThemeData` and `ThemeData.copyWith()`
(Object? is used for the moment to minimize Google tests failure. A
follow-up PR will replace `Object?` with `InputDecorationThemeData`.
- Addresses the "theme normalization" sub-project within #91772.
A migration guide will be created on website repo.
de3f804590