Issue #2072553 by legolasbo: Remove Unused local variable () from...

Issue #2072553 by legolasbo: Remove Unused local variable () from /core/modules/file/lib/Drupal/file/Plugin/field/widget/FileWidget.php.

core/modules/file/lib/Drupal/file/Plugin/field/widget/FileWidget.php

@@ -89,9 +89,6 @@ protected function formMultipleElements(EntityInterface $entity, FieldInterface
         break;
     }
 
-    $id_prefix = implode('-', array_merge($parents, array($field_name)));
-    $wrapper_id = drupal_html_id($id_prefix . '-add-more-wrapper');
-
     $title = check_plain($this->fieldDefinition->getFieldLabel());
     $description = field_filter_xss($this->fieldDefinition->getFieldDescription());