Revert "Update FormProxy:add declaration"

This reverts commit 2cd05771a36030dff3d88506fb20b3fb8cb40f18.

Form/EventListener/FormProxy.php

@@ -63,7 +63,7 @@ class FormProxy implements \IteratorAggregate, FormInterface
         return $this->__call('hasParent', func_get_args());
     }
 
-    public function add($child, $type = null, array $options = array())
+    public function add(FormInterface $child)
     {
         return $this->__call('add', func_get_args());
     }