patch 8.2.1432: various inconsistencies in test files

Problem:    Various inconsistencies in test files.
Solution:   Add modelines where they were missing.  Use Check commands instead
            of silently skipping over tests.  Adjust indents and comments.
            (Ken Takata, closes #6695)
diff --git a/src/testdir/test_winbuf_close.vim b/src/testdir/test_winbuf_close.vim
index 643c106..3f67e88 100644
--- a/src/testdir/test_winbuf_close.vim
+++ b/src/testdir/test_winbuf_close.vim
@@ -213,3 +213,4 @@
   call assert_equal(w, win_getid(), "Did not return to original window after opening and closing a window")
 endfunc
 
+" vim: shiftwidth=2 sts=2 expandtab