diff --git a/core/modules/views/lib/Drupal/views/Plugin/views/field/Custom.php b/core/modules/views/lib/Drupal/views/Plugin/views/field/Custom.php
index f580733..f41efeb 100644
--- a/core/modules/views/lib/Drupal/views/Plugin/views/field/Custom.php
+++ b/core/modules/views/lib/Drupal/views/Plugin/views/field/Custom.php
@@ -38,7 +38,7 @@ public function buildOptionsForm(&$form, &$form_state) {
     unset($form['alter']['alter_text']);
     unset($form['alter']['text']['#states']);
     unset($form['alter']['help']['#states']);
-    $form['#pre_render'][] = 'views_handler_field_custom_pre_render_move_text';
+    $form['#pre_render'][] = array($this, 'preRender');
   }
 
   function render($values) {
@@ -46,4 +46,19 @@ function render($values) {
     return $this->options['alter']['text'];
   }
 
+  /**
+   * Prerender function to move the textarea to the top of a form.
+   *
+   * @param array $form
+   *   The form build array.
+   */
+  public function preRender($form) {
+    $form['text'] = $form['alter']['text'];
+    $form['help'] = $form['alter']['help'];
+    unset($form['alter']['text']);
+    unset($form['alter']['help']);
+
+    return $form;
+  }
+
 }
diff --git a/core/modules/views/views.module b/core/modules/views/views.module
index 61826f8..a772b05 100644
--- a/core/modules/views/views.module
+++ b/core/modules/views/views.module
@@ -1729,18 +1729,6 @@ function views_element_validate_tags($element, &$form_state) {
 }
 
 /**
- * Prerender function to move the textarea to the top.
- */
-function views_handler_field_custom_pre_render_move_text($form) {
-  $form['text'] = $form['alter']['text'];
-  $form['help'] = $form['alter']['help'];
-  unset($form['alter']['text']);
-  unset($form['alter']['help']);
-
-  return $form;
-}
-
-/**
  * Helper function: Return an array of formatter options for a field type.
  *
  * Borrowed from field_ui.