Make shift-click checkbox range selection work in both directions. props c3mdigital, SergeyBiryukov. fixes #23427.

Built from https://develop.svn.wordpress.org/trunk@25141


git-svn-id: http://core.svn.wordpress.org/trunk@25121 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-admin/js/common.js

@@ -160,7 +160,7 @@ $('.contextual-help-tabs').delegate('a', 'click focus', function(e) {
 });
 
 $(document).ready( function() {
-	var lastClicked = false, checks, first, last, checked, menu = $('#adminmenu'), mobileEvent,
+	var lastClicked = false, checks, first, last, checked, sliced, menu = $('#adminmenu'), mobileEvent,
 		pageInput = $('input.current-page'), currentPage = pageInput.val();
 
 	// when the menu is folded, make the fly-out submenu header clickable
@@ -286,7 +286,8 @@ $(document).ready( function() {
 			last = checks.index( this );
 			checked = $(this).prop('checked');
 			if ( 0 < first && 0 < last && first != last ) {
-				checks.slice( first, last ).prop( 'checked', function(){
+				sliced = ( last > first ) ? checks.slice( first, last ) : checks.slice( last, first );
+				sliced.prop( 'checked', function() {
 					if ( $(this).closest('tr').is(':visible') )
 						return checked;