patch 8.2.0615: regexp benchmark stest is old style

Problem:    Regexp benchmark stest is old style.
Solution:   Make it a new style test.  Fix using a NULL list.  Add more tests.
            (Yegappan Lakshmanan, closes #5963)
diff --git a/src/testdir/test_window_cmd.vim b/src/testdir/test_window_cmd.vim
index a28c00a..4927842 100644
--- a/src/testdir/test_window_cmd.vim
+++ b/src/testdir/test_window_cmd.vim
@@ -1079,4 +1079,16 @@
   call Run_noroom_for_newwindow_test('v')
 endfunc
 
+" Test for various wincmd failures
+func Test_wincmd_fails()
+  only!
+  call assert_beeps("normal \<C-W>w")
+  call assert_beeps("normal \<C-W>p")
+  call assert_beeps("normal \<C-W>gk")
+  call assert_beeps("normal \<C-W>r")
+  call assert_beeps("normal \<C-W>K")
+  call assert_beeps("normal \<C-W>H")
+  call assert_beeps("normal \<C-W>2gt")
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab