patch 9.0.0673: first line wong with 'smoothscroll' and 'scrolloff' zero

Problem:    First line not scrolled properly with 'smoothscroll' and
            'scrolloff' zero and using "k".
Solution:   Make sure the cursor position is visible.
diff --git a/src/testdir/test_scroll_opt.vim b/src/testdir/test_scroll_opt.vim
index d11d0be..0292fa1 100644
--- a/src/testdir/test_scroll_opt.vim
+++ b/src/testdir/test_scroll_opt.vim
@@ -181,6 +181,7 @@
 
   call VerifyScreenDump(buf, 'Test_smooth_wrap_1', {})
 
+  " moving cursor down - whole bottom line shows
   call term_sendkeys(buf, "j")
   call VerifyScreenDump(buf, 'Test_smooth_wrap_2', {})
 
@@ -190,6 +191,10 @@
   call term_sendkeys(buf, "G")
   call VerifyScreenDump(buf, 'Test_smooth_wrap_4', {})
 
+  " moving cursor up - whole top line shows
+  call term_sendkeys(buf, "2k")
+  call VerifyScreenDump(buf, 'Test_smooth_wrap_5', {})
+
   call StopVimInTerminal(buf)
 endfunc