patch 8.1.1953: 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_true_false.vim b/src/testdir/test_true_false.vim
index a23f2cc..346b432 100644
--- a/src/testdir/test_true_false.vim
+++ b/src/testdir/test_true_false.vim
@@ -100,7 +100,7 @@
   call Try_arg_true_false('maparg("asdf", "i", %v%)', "", "asdff")
   call Try_arg_true_false('FilterMapArg(maparg("asdf", "i", 1, %v%))', "asdff", {'rhs': 'asdff'})
 
-  call Try_arg_true_false('hasmapto("asdf", "i", %v%)', 0, 1)
+  call Try_arg_true_false('"asdf"->hasmapto("i", %v%)', 0, 1)
 
   new colored
   call setline(1, '<here>')