Merge branch 't/12843'

Author: Reinmar

tests/tickets/12812/1.html

@@ -1 +1,5 @@
-<iframe src="http://sub.ckeditor.dev:1030%TEST_DIR%/_assets/inlineeditor.html" width="800" height="400"></iframe>
+<script>
+	var port = location.port ? ( ':' + location.port ) : '';
+
+	document.write( '<iframe src="http://sub.ckeditor.dev' + port + '%TEST_DIR%_assets/inlineeditor.html" width="800" height="400"></iframe>' );
+</script>