patch 8.1.1925: more functions can be used as methods

Problem:    More functions can be used as methods.
Solution:   Make various functions usable as a method.
diff --git a/src/testdir/test_jumplist.vim b/src/testdir/test_jumplist.vim
index be1af5e..9cfbbe2 100644
--- a/src/testdir/test_jumplist.vim
+++ b/src/testdir/test_jumplist.vim
@@ -39,7 +39,7 @@
   " Traverse the jump list and verify the results
   5
   exe "normal \<C-O>"
-  call assert_equal(2, getjumplist(1)[1])
+  call assert_equal(2, 1->getjumplist()[1])
   exe "normal 2\<C-O>"
   call assert_equal(0, getjumplist(1, 1)[1])
   exe "normal 3\<C-I>"