Nav menus: Provide visual feedback when attempting to add an empty custom link.

props pragunbhutani for the initial patch.
fixes #18517.

Built from https://develop.svn.wordpress.org/trunk@32690


git-svn-id: http://core.svn.wordpress.org/trunk@32660 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-admin/js/nav-menu.js

@@ -817,6 +817,8 @@ var wpNavMenu;
 				}
 			});
 			$('#add-custom-links input[type="text"]').keypress(function(e){
+				$('#customlinkdiv').removeClass('form-invalid');
+
 				if ( e.keyCode === 13 ) {
 					e.preventDefault();
 					$( '#submit-customlinkdiv' ).click();
@@ -919,8 +921,10 @@ var wpNavMenu;
 
 			processMethod = processMethod || api.addMenuItemToBottom;
 
-			if ( '' === url || 'http://' == url )
+			if ( '' === url || 'http://' == url ) {
+				$('#customlinkdiv').addClass('form-invalid');
 				return false;
+			}
 
 			// Show the ajax spinner
 			$( '.customlinkdiv .spinner' ).addClass( 'is-active' );

wp-includes/version.php

@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.3-alpha-32689';
+$wp_version = '4.3-alpha-32690';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.