fix(firebase_messaging): Stream new token via onTokenRefresh when getToken invoked for iOS. (#8166)

Author: russellwheatley

packages/firebase_messaging/firebase_messaging/ios/Classes/FLTFirebaseMessagingPlugin.m

@@ -599,10 +599,18 @@ - (void)messagingGetNotificationSettings:(id)arguments
 
 - (void)messagingGetToken:(id)arguments withMethodCallResult:(FLTFirebaseMethodCallResult *)result {
   FIRMessaging *messaging = [FIRMessaging messaging];
+
+  // Keep behaviour consistent with android platform, newly retrieved tokens are streamed via
+  // onTokenRefresh
+  bool refreshToken = messaging.FCMToken == nil ? YES : NO;
   [messaging tokenWithCompletion:^(NSString *_Nullable token, NSError *_Nullable error) {
     if (error != nil) {
       result.error(nil, nil, nil, error);
     } else {
+      if (refreshToken) {
+        [self->_channel invokeMethod:@"Messaging#onTokenRefresh" arguments:token];
+      }
+
       result.success(@{@"token" : token});
     }
   }];