vim-patch:8.2.3856: Vim9: not enough tests

Problem:    Vim9: not enough tests.
Solution:   Run more expression tests also with Vim9. Fix an uncovered
            problem.

fea43e44c0

Co-authored-by: Bram Moolenaar <Bram@vim.org>

test/old/testdir/vim9.vim

@@ -34,6 +34,14 @@ func CheckScriptSuccess(lines)
   endtry
 endfunc
 
+func CheckDefAndScriptSuccess(lines)
+  return
+endfunc
+
+func CheckDefAndScriptFailure(lines, error, lnum = -3)
+  return
+endfunc
+
 func CheckDefExecAndScriptFailure(lines, error, lnum = -3)
   return
 endfunc
@@ -85,6 +93,14 @@ func CheckTransLegacySuccess(lines)
   call CheckLegacySuccess(legacylines)
 endfunc
 
+func CheckTransDefSuccess(lines)
+  return
+endfunc
+
+func CheckTransVim9Success(lines)
+  return
+endfunc
+
 " Execute "lines" in a legacy function
 " Use 'VAR' for a declaration.
 " Use 'LET' for an assignment