Widgets: add a function, is_registered_sidebar() - helps us avoid touching the $wp_registered_sidebars global.

Props GaryJ, wonderboymusic.
Fixes #24878.


git-svn-id: https://develop.svn.wordpress.org/trunk@35102 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-admin/widgets.php

@@ -89,7 +89,7 @@ foreach ( $sidebars_widgets as $sidebar_id => $widgets ) {
 	if ( 'wp_inactive_widgets' == $sidebar_id )
 		continue;
 
-	if ( !isset( $wp_registered_sidebars[ $sidebar_id ] ) ) {
+	if ( ! is_registered_sidebar( $sidebar_id ) ) {
 		if ( ! empty( $widgets ) ) { // register the inactive_widgets area as sidebar
 			register_sidebar(array(
 				'name' => __( 'Inactive Sidebar (not used)' ),
@@ -155,7 +155,7 @@ if ( isset($_POST['savewidget']) || isset($_POST['removewidget']) ) {
 
 		/**
 		 * Fires immediately after a widget has been marked for deletion.
-		 * 
+		 *
 		 * @since 4.4.0
 		 *
 		 * @param string $widget_id  ID of the widget marked for deletion.