Customizer: In menus, reset results when closing the 'add items' panel.

Trigger a keyup event when clearing the search field in response to closing the add item panel. The keyup event triggers a search and resets the results. Previously, the search field was cleared while the potentially blank search results were left in place making it impossible to select new menu items.

Merge of [42744] to the 4.9 branch.

Props Blair jersyer, aranwer104, afercia.
See #43333.
Built from https://develop.svn.wordpress.org/branches/4.9@42846


git-svn-id: http://core.svn.wordpress.org/branches/4.9@42676 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-admin/js/customize-nav-menus.js

@@ -723,7 +723,7 @@
 			$( 'body' ).removeClass( 'adding-menu-items' );
 			$( '#available-menu-items .menu-item-handle.item-added' ).removeClass( 'item-added' );
 
-			this.$search.val( '' );
+			this.$search.val( '' ).trigger( 'keyup' );
 		},
 
 		// Add a few keyboard enhancements to the panel.

wp-includes/version.php

@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.9.5-alpha-42845';
+$wp_version = '4.9.5-alpha-42846';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.