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_getvar.vim b/src/testdir/test_getvar.vim
index e9868c7..5a96548 100644
--- a/src/testdir/test_getvar.vim
+++ b/src/testdir/test_getvar.vim
@@ -12,8 +12,8 @@
   let def_str = "Chance"
   call assert_equal('Dance', getwinvar(1, 'var_str'))
   call assert_equal('Dance', getwinvar(1, 'var_str', def_str))
-  call assert_equal({'var_str': 'Dance'}, getwinvar(1, ''))
-  call assert_equal({'var_str': 'Dance'}, getwinvar(1, '', def_str))
+  call assert_equal({'var_str': 'Dance'}, 1->getwinvar(''))
+  call assert_equal({'var_str': 'Dance'}, 1->getwinvar('', def_str))
   unlet w:var_str
   call assert_equal('Chance', getwinvar(1, 'var_str', def_str))
   call assert_equal({}, getwinvar(1, ''))