diff --git a/src/Symfony/Component/Form/Extension/Core/EventListener/ResizeFormListener.php b/src/Symfony/Component/Form/Extension/Core/EventListener/ResizeFormListener.php
index d2b13e4a96..f1c39db245 100644
--- a/src/Symfony/Component/Form/Extension/Core/EventListener/ResizeFormListener.php
+++ b/src/Symfony/Component/Form/Extension/Core/EventListener/ResizeFormListener.php
@@ -139,21 +139,9 @@ class ResizeFormListener implements EventSubscriberInterface
         // The data mapper only adds, but does not remove items, so do this
         // here
         if ($this->allowDelete) {
-            if ($data instanceof \IteratorAggregate) {
-                $iter = $data->getIterator();
-                while ($iter->valid()) {
-                    $name = $iter->key();
-                    if ($form->has($name)) {
-                        $iter->next();
-                    } else {
-                        $iter->offsetUnset($name);
-                    }
-                }
-            } else {
-                foreach ($data as $name => $child) {
-                    if (!$form->has($name)) {
-                        unset($data[$name]);
-                    }
+            foreach ($data as $name => $child) {
+                if (!$form->has($name)) {
+                    unset($data[$name]);
                 }
             }
         }