fixed a bug modal viewController was not deallocated when to call dismissAllModals (#2843)

ios/RCCManagerModule.m

                                    
                                    dispatch_semaphore_wait(dismiss_sema, DISPATCH_TIME_FOREVER);
                                }
-                               else if (counter == allPresentedViewControllers.count && allPresentedViewControllers.count > 0)
-                               {
-                                   [allPresentedViewControllers removeAllObjects];
-                                   
-                                   if (resolve != nil) {
-                                       dispatch_async(dispatch_get_main_queue(), ^
-                                                      {
-                                                          resolve(nil);
-                                                      });
+                               else {
+                                   if (rootViewController != viewController) {
+                                       [[RCCManager sharedIntance] unregisterController:viewController];
+                                   }
+                                   if (counter == allPresentedViewControllers.count && allPresentedViewControllers.count > 0)
+                                   {
+                                       [allPresentedViewControllers removeAllObjects];
+
+                                       if (resolve != nil) {
+                                           dispatch_async(dispatch_get_main_queue(), ^
+                                                          {
+                                                              resolve(nil);
+                                                          });
+                                       }
                                    }
                                }
                            }