[Form] add type for FileField class

src/Symfony/Component/Form/FileField.php

@@ -16,6 +16,16 @@ namespace Symfony\Component\Form;
  */
 class FileField extends InputField
 {
+    /**
+     * {@inheritDoc}
+     */
+    public function __construct($key, array $options = array())
+    {
+        $options['type'] = 'file';
+
+        parent::__construct($key, $options);
+    }
+
     /**
      * {@inheritDoc}
      */