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_quickfix.vim b/src/testdir/test_quickfix.vim
index 402a96d..f240398 100644
--- a/src/testdir/test_quickfix.vim
+++ b/src/testdir/test_quickfix.vim
@@ -517,7 +517,7 @@
   call test_alloc_fail(GetAllocId('qf_dirname_start'), 0, 0)
   call assert_fails('vimgrep vim runtest.vim', 'E342:')
 
-  call test_alloc_fail(GetAllocId('qf_dirname_now'), 0, 0)
+  call GetAllocId('qf_dirname_now')->test_alloc_fail(0, 0)
   call assert_fails('vimgrep vim runtest.vim', 'E342:')
 
   call test_alloc_fail(GetAllocId('qf_namebuf'), 0, 0)