Conditionally add AYS to leaving shiny updates

When a shiny update is happening or pending, we should make sure users don't accidentally leave the page. This simple notification should help prevent users from accidentally not updating when they want to update.

See #31769
Props ericlewis and adamsilverstein for initial patch


Built from https://develop.svn.wordpress.org/trunk@32052


git-svn-id: http://core.svn.wordpress.org/trunk@32031 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-admin/js/updates.js

@@ -510,4 +510,14 @@ window.wp = window.wp || {};
 
 	} );
 
+	/*
+	 * If an update is on-going and a user attempts to leave the page,
+	 * open an "Are you sure?" alert.
+	 */
+	$( window ).on( 'beforeunload', function() {
+		if ( wp.updates.updateLock ) {
+			return wp.updates.l10n.beforeunload;
+		}
+	});
+
 })( jQuery, window.wp, window.pagenow, window.ajaxurl );

wp-includes/version.php

@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.2-beta4-32051';
+$wp_version = '4.2-beta4-32052';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.