patch 8.2.4260: Vim9: can still use a global function without g:

Problem:    Vim9: can still use a global function without g: at the script
            level.
Solution:   Also check for g: at the script level. (issue #9637)
diff --git a/src/testdir/test_vim9_builtin.vim b/src/testdir/test_vim9_builtin.vim
index 16be67c..d6b42bb 100644
--- a/src/testdir/test_vim9_builtin.vim
+++ b/src/testdir/test_vim9_builtin.vim
@@ -1303,7 +1303,7 @@
 enddef
 
 def Test_filter_wrong_dict_key_type()
-  assert_fails('Wrong_dict_key_type([1, v:null, 3])', 'E1013:')
+  assert_fails('g:Wrong_dict_key_type([1, v:null, 3])', 'E1013:')
 enddef
 
 def Test_filter_return_type()