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_scroll_opt.vim b/src/testdir/test_scroll_opt.vim
index 77920eb..bf28123 100644
--- a/src/testdir/test_scroll_opt.vim
+++ b/src/testdir/test_scroll_opt.vim
@@ -1,5 +1,4 @@
 " Test for reset 'scroll'
-"
 
 func Test_reset_scroll()
   let scr = &l:scroll
@@ -34,3 +33,5 @@
 
   quit!
 endfunc
+
+" vim: shiftwidth=2 sts=2 expandtab