patch 8.1.1952: more functions can be used as a method

Problem:    More functions can be used as a method.
Solution:   Allow more functions to be used as a method.
diff --git a/src/testdir/test_glob2regpat.vim b/src/testdir/test_glob2regpat.vim
index e6e41f1..29c8d99 100644
--- a/src/testdir/test_glob2regpat.vim
+++ b/src/testdir/test_glob2regpat.vim
@@ -8,7 +8,7 @@
 
 func Test_glob2regpat_valid()
   call assert_equal('^foo\.', glob2regpat('foo.*'))
-  call assert_equal('^foo.$', glob2regpat('foo?'))
+  call assert_equal('^foo.$', 'foo?'->glob2regpat())
   call assert_equal('\.vim$', glob2regpat('*.vim'))
   call assert_equal('^[abc]$', glob2regpat('[abc]'))
   call assert_equal('^foo bar$', glob2regpat('foo\ bar'))