Added is-active class to Orders when looking at individual order under My Account.

includes/wc-account-functions.php

@@ -149,6 +149,8 @@ function wc_get_account_menu_item_classes( $endpoint ) {
 	$current = isset( $wp->query_vars[ $endpoint ] );
 	if ( 'dashboard' === $endpoint && ( isset( $wp->query_vars['page'] ) || empty( $wp->query_vars ) ) ) {
 		$current = true; // Dashboard is not an endpoint, so needs a custom check.
+	} elseif ( 'orders' === $endpoint && isset( $wp->query_vars['view-order'] ) ) {
+		$current = true; // When looking at individual order, highlight Orders list item (to signify where in the menu the user currently is).
 	}
 
 	if ( $current ) {