The platform the material widgets should adapt to target.
Defaults to the current platform. This should be used in order to style UI elements according to platform conventions.
Platform.defaultTargetPlatform should be used directly instead only in
rare cases where it's necessary to determine behavior based on the
dart.io.Platform.environment should be used when it's critical
to actually know the current platform, without any overrides possible (for
example, when a system API is about to be called).
final TargetPlatform platform