pushFlutterRouteForResult method
Like pushFlutterRoute, but completes with the result the pushed
screen pops with (null when dismissed without one).
The value is in wire encoding; generated routes with a result type
expose a typed pushForResult() that decodes it.
Implementation
@override
Future<Object?> pushFlutterRouteForResult(PageSettings page) async {
pushedPages.add(page);
return resultsByRouteId[page.routeId];
}