Index: wp-includes/nav-menu-template.php
===================================================================
--- wp-includes/nav-menu-template.php	(revision 14896)
+++ wp-includes/nav-menu-template.php	(working copy)
@@ -75,6 +75,11 @@
 		if ( 'custom' != $item->type ) {
 			$classes[] = 'menu-item-object-' . $item->object;
 			$classes[] = 'menu-item-object-' . $item->type . '-' . $item->object_id;
+			if ( 'post_type' == $item->type && 'page' == $item->object ) {
+				// Back compat classes
+				$classes[] = 'page_item';
+				$classes[] = 'page-item-' . $item->object_id;
+			}
 		}
 
 		$classes = join( ' ', apply_filters( 'nav_menu_css_class', array_filter( $classes ), $item ) );