patch 9.0.1515: reverse() does not work for a String

Problem:    reverse() does not work for a String.
Solution:   Implement reverse() for a String. (Yegappan Lakshmanan,
            closes #12179)
diff --git a/src/testdir/test_listdict.vim b/src/testdir/test_listdict.vim
index b550a43..e29c351 100644
--- a/src/testdir/test_listdict.vim
+++ b/src/testdir/test_listdict.vim
@@ -981,7 +981,7 @@
   END
   call v9.CheckLegacyAndVim9Success(lines)
 
-  call assert_fails('call reverse("")', 'E899:')
+  call assert_fails('call reverse({})', 'E899:')
   call assert_fails('call uniq([1, 2], {x, y -> []})', 'E745:')
   call assert_fails("call sort([1, 2], function('min'), 1)", "E1206:")
   call assert_fails("call sort([1, 2], function('invalid_func'))", "E700:")