Ticket #18456: 18456.patch

wp-includes/class-wp-editor.php

@@ -291 +291 @@
 
                                         // load editor_style.css if the current theme supports it
                                         if ( ! empty( $editor_styles ) && is_array( $editor_styles ) ) {
+                                                $editor_styles = array_unique( $editor_styles );
                                                 $mce_css = array();
                                                 $style_uri = get_stylesheet_directory_uri();
                                                 if ( ! is_child_theme() ) {