added support for 2fa login with browser flow

test/push/push_dual_registration_test.dart

@@ -53,6 +53,45 @@ void main() {
     });
   });
 
+  group('registrationTypesFor', () {
+    test('password accounts maintain both registrations', () {
+      expect(
+        PushRegistration.registrationTypesFor(
+          usesLoginFlow: false,
+          hasTalkAppPassword: false,
+        ),
+        PushRegistrationType.values,
+      );
+      expect(
+        PushRegistration.registrationTypesFor(
+          usesLoginFlow: false,
+          hasTalkAppPassword: true,
+        ),
+        PushRegistrationType.values,
+      );
+    });
+
+    test('flow account without talk app password is talk-only', () {
+      expect(
+        PushRegistration.registrationTypesFor(
+          usesLoginFlow: true,
+          hasTalkAppPassword: false,
+        ),
+        [PushRegistrationType.talk],
+      );
+    });
+
+    test('flow account with second (talk) app password maintains both', () {
+      expect(
+        PushRegistration.registrationTypesFor(
+          usesLoginFlow: true,
+          hasTalkAppPassword: true,
+        ),
+        PushRegistrationType.values,
+      );
+    });
+  });
+
   group('pushTokenVariant', () {
     test('general uses the raw token, talk appends the suffix', () {
       expect(pushTokenVariant('tok', PushRegistrationType.general), 'tok');