patch 8.1.2011: more functions can be used as methods

Problem:    More functions can be used as methods.
Solution:   Make various functions usable as a method.  Make the window
            command test faster.
diff --git a/src/testdir/test_vimscript.vim b/src/testdir/test_vimscript.vim
index 8dc00f2..18790d2 100644
--- a/src/testdir/test_vimscript.vim
+++ b/src/testdir/test_vimscript.vim
@@ -1596,7 +1596,7 @@
     call assert_equal(1, test_refcount(x))
 
     let x = {}
-    call assert_equal(1, test_refcount(x))
+    call assert_equal(1, x->test_refcount())
 
     let x = 0zff
     call assert_equal(1, test_refcount(x))