Remove unnecessary nullable qualifiers

Author: mvanbeusekom

permission_handler_html/example/analysis_options.yaml

@@ -10,9 +10,9 @@ import 'web_delegate.dart';
 
 /// Platform implementation of the permission_handler Flutter plugin.
 class WebPermissionHandler extends PermissionHandlerPlatform {
-  static final web.MediaDevices? _devices = web.window.navigator.mediaDevices;
+  static final web.MediaDevices _devices = web.window.navigator.mediaDevices;
   static final web.Geolocation _geolocation = web.window.navigator.geolocation;
-  static final web.Permissions? _htmlPermissions =
+  static final web.Permissions _htmlPermissions =
       web.window.navigator.permissions;
 
   final WebDelegate _webDelegate;