fix(app-check, web): More explicit interop types

packages/firebase_app_check/firebase_app_check_web/lib/firebase_app_check_web.dart

@@ -157,7 +157,7 @@ class FirebaseAppCheckWeb extends FirebaseAppCheckPlatform {
   @override
   Future<String?> getToken(bool forceRefresh) async {
     return convertWebExceptions<Future<String?>>(() async {
-      app_check_interop.AppCheckTokenResult result =
+      app_check_interop.AppCheckTokenResultJsImpl result =
           await _delegate!.getToken(forceRefresh);
       return result.token.toDart;
     });
@@ -166,7 +166,7 @@ class FirebaseAppCheckWeb extends FirebaseAppCheckPlatform {
   @override
   Future<String> getLimitedUseToken() async {
     return convertWebExceptions<Future<String>>(() async {
-      app_check_interop.AppCheckTokenResult result =
+      app_check_interop.AppCheckTokenResultJsImpl result =
           await _delegate!.getLimitedUseToken();
       return result.token.toDart;
     });

packages/firebase_app_check/firebase_app_check_web/lib/src/interop/app_check.dart

@@ -58,22 +58,20 @@ class AppCheck extends JsObjectWrapper<app_check_interop.AppCheckJsImpl> {
         isTokenAutoRefreshEnabled.toJS,
       );
 
-  Future<app_check_interop.AppCheckTokenResult> getToken(bool? forceRefresh) =>
-      app_check_interop.getToken(jsObject, forceRefresh?.toJS).toDart.then(
-            (value) => value! as app_check_interop.AppCheckTokenResult,
-          );
+  Future<app_check_interop.AppCheckTokenResultJsImpl> getToken(
+    bool? forceRefresh,
+  ) =>
+      app_check_interop.getToken(jsObject, forceRefresh?.toJS).toDart;
 
-  Future<app_check_interop.AppCheckTokenResult> getLimitedUseToken() =>
-      app_check_interop.getLimitedUseToken(jsObject).toDart.then(
-            (value) => value! as app_check_interop.AppCheckTokenResult,
-          );
+  Future<app_check_interop.AppCheckTokenResultJsImpl> getLimitedUseToken() =>
+      app_check_interop.getLimitedUseToken(jsObject).toDart;
 
   JSFunction? _idTokenChangedUnsubscribe;
 
-  StreamController<app_check_interop.AppCheckTokenResult>?
+  StreamController<app_check_interop.AppCheckTokenResultJsImpl>?
       get idTokenChangedController => _idTokenChangedController;
 
-  StreamController<app_check_interop.AppCheckTokenResult>?
+  StreamController<app_check_interop.AppCheckTokenResultJsImpl>?
       // ignore: close_sinks
       _idTokenChangedController;
 
@@ -92,11 +90,14 @@ class AppCheck extends JsObjectWrapper<app_check_interop.AppCheckJsImpl> {
     return 'no-op';
   }
 
-  Stream<app_check_interop.AppCheckTokenResult> onTokenChanged(String appName) {
+  Stream<app_check_interop.AppCheckTokenResultJsImpl> onTokenChanged(
+    String appName,
+  ) {
     final appCheckWindowsKey = _appCheckWindowsKey(appName);
     unsubscribeWindowsListener(appCheckWindowsKey);
     if (_idTokenChangedController == null) {
-      final nextWrapper = ((app_check_interop.AppCheckTokenResult result) {
+      final nextWrapper =
+          ((app_check_interop.AppCheckTokenResultJsImpl result) {
         _idTokenChangedController!.add(result);
       }).toJS;
 
@@ -119,8 +120,8 @@ class AppCheck extends JsObjectWrapper<app_check_interop.AppCheckJsImpl> {
         removeWindowsListener(appCheckWindowsKey);
       }
 
-      _idTokenChangedController =
-          StreamController<app_check_interop.AppCheckTokenResult>.broadcast(
+      _idTokenChangedController = StreamController<
+          app_check_interop.AppCheckTokenResultJsImpl>.broadcast(
         onListen: startListen,
         onCancel: stopListen,
         sync: true,

packages/firebase_app_check/firebase_app_check_web/lib/src/interop/app_check_interop.dart

@@ -21,14 +21,14 @@ external AppCheckJsImpl initializeAppCheck(
 
 @JS()
 @staticInterop
-external JSPromise /* AppCheckTokenResult */ getToken(
+external JSPromise<AppCheckTokenResultJsImpl> getToken(
   AppCheckJsImpl? appCheck,
   JSBoolean? forceRefresh,
 );
 
 @JS()
 @staticInterop
-external JSPromise /* AppCheckTokenResult */ getLimitedUseToken(
+external JSPromise<AppCheckTokenResultJsImpl> getLimitedUseToken(
   AppCheckJsImpl? appCheck,
 );
 
@@ -64,11 +64,7 @@ class ReCaptchaEnterpriseProvider implements ReCaptchaProvider {
   external factory ReCaptchaEnterpriseProvider(JSString recaptchaKey);
 }
 
-@JS()
-@staticInterop
-abstract class AppCheckTokenResult {}
-
-extension AppCheckTokenResultJsImplX on AppCheckTokenResult {
+extension type AppCheckTokenResultJsImpl._(JSObject _) implements JSObject {
   external JSString get token;
 }
 
@@ -88,10 +84,6 @@ extension AppCheckOptionsJsImplX on AppCheckOptions {
   external ReCaptchaProvider get provider;
 }
 
-@JS('AppCheck')
-@staticInterop
-abstract class AppCheckJsImpl {}
-
-extension AppCheckJsImplX on AppCheckJsImpl {
+extension type AppCheckJsImpl._(JSObject _) implements JSObject {
   external AppJsImpl get app;
 }

tests/integration_test/firebase_app_check/firebase_app_check_e2e_test.dart

@@ -44,9 +44,7 @@ void main() {
             // Needs a debug token pasted in the Firebase console to work so we catch the exception.
             expect(exception, isA<FirebaseException>());
           }
-          // This will fail until this is resolved: https://github.com/dart-lang/sdk/issues/52572
         },
-        skip: kIsWeb,
       );
 
       test(
@@ -73,9 +71,7 @@ void main() {
             // Needs a debug token pasted in the Firebase console to work so we catch the exception.
             expect(exception, isA<FirebaseException>());
           }
-          // This will fail until this is resolved: https://github.com/dart-lang/sdk/issues/52572
         },
-        skip: kIsWeb,
       );
 
       test(