Remove redundant "$request = $this->requestStack->getCurrentRequest();" code

core/lib/Drupal/Core/Form/FormBuilder.php

@@ -302,7 +302,6 @@ public function buildForm($form_arg, FormStateInterface &$form_state) {
     }
 
     // If this form is an AJAX request, disable all form redirects.
-    $request = $this->requestStack->getCurrentRequest();
     if ($ajax_form_request = $request->query->has(static::AJAX_FORM_REQUEST)) {
       $form_state->disableRedirect();
     }