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_delete.vim b/src/testdir/test_delete.vim
index 0ab5164..b23a3bd 100644
--- a/src/testdir/test_delete.vim
+++ b/src/testdir/test_delete.vim
@@ -110,3 +110,5 @@
   call assert_fails('call delete('''')', 'E474:')
   call assert_fails('call delete(''foo'', 0)', 'E15:')
 endfunc
+
+" vim: shiftwidth=2 sts=2 expandtab