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_bufwintabinfo.vim b/src/testdir/test_bufwintabinfo.vim
index d9b3691..4e2c5d2 100644
--- a/src/testdir/test_bufwintabinfo.vim
+++ b/src/testdir/test_bufwintabinfo.vim
@@ -77,7 +77,7 @@
 
     call assert_equal('green', winlist[2].variables.signal)
     call assert_equal(w4_id, winlist[3].winid)
-    let winfo = getwininfo(w5_id)[0]
+    let winfo = w5_id->getwininfo()[0]
     call assert_equal(2, winfo.tabnr)
     call assert_equal([], getwininfo(3))