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_display.vim b/src/testdir/test_display.vim
index 1e2ed45..97b0a9e 100644
--- a/src/testdir/test_display.vim
+++ b/src/testdir/test_display.vim
@@ -1,4 +1,5 @@
 " Test for displaying stuff
+
 if !has('gui_running') && has('unix')
   set term=ansi
 endif
@@ -243,3 +244,5 @@
   call StopVimInTerminal(buf)
   call delete(filename)
 endfunc
+
+" vim: shiftwidth=2 sts=2 expandtab