From 1d7714d923ccb5eae188cabb47da0d47d55735f8 Mon Sep 17 00:00:00 2001
From: Andrew Nacin <nacin@git.wordpress.org>
Date: Fri, 30 Mar 2012 13:10:52 +0000
Subject: [PATCH] Check for is_rtl() existence before checking it in the
 fallback condition in wp_admin_css(). Prevents fatal errors when plugins call
 wp_admin_css() on a non-existent (probably removed) stylesheet. props
 SergeyBiryukov, fixes #19913.

git-svn-id: https://develop.svn.wordpress.org/trunk@20326 602fd350-edb4-49c9-b593-d223f7449a82
---
 wp-includes/general-template.php | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/wp-includes/general-template.php b/wp-includes/general-template.php
index e86963e6ee..63e6d6524a 100644
--- a/wp-includes/general-template.php
+++ b/wp-includes/general-template.php
@@ -2100,7 +2100,7 @@ function wp_admin_css( $file = 'wp-admin', $force_echo = false ) {
 	}
 
 	echo apply_filters( 'wp_admin_css', "<link rel='stylesheet' href='" . esc_url( wp_admin_css_uri( $file ) ) . "' type='text/css' />\n", $file );
-	if ( is_rtl() )
+	if ( function_exists( 'is_rtl' ) && is_rtl() )
 		echo apply_filters( 'wp_admin_css', "<link rel='stylesheet' href='" . esc_url( wp_admin_css_uri( "$file-rtl" ) ) . "' type='text/css' />\n", "$file-rtl" );
 }