patch 8.2.3810: Vim9: expr4 test fails on MS-Windows

Problem:    Vim9: expr4 test fails on MS-Windows.
Solution:   Do not give an error for a missing function name when skipping.
diff --git a/src/testdir/test_vim9_expr.vim b/src/testdir/test_vim9_expr.vim
index a357b11..1f695bc 100644
--- a/src/testdir/test_vim9_expr.vim
+++ b/src/testdir/test_vim9_expr.vim
@@ -646,8 +646,16 @@
       assert_equal(false, function('g:Test_expr4_equal', [123]) == function('g:Test_expr4_is', [123]))
       assert_equal(false, function('g:Test_expr4_equal', [123]) == function('g:Test_expr4_equal', [999]))
 
-      # TODO: this unexpectedly sometimes fails on Appveyor
-      if !has('win32')
+      if true
+        var OneFunc: func
+        var TwoFunc: func
+        OneFunc = function('len')
+        TwoFunc = function('len')
+        assert_equal(true, OneFunc('abc') == TwoFunc('123'))
+      endif
+
+      # check this doesn't fail when skipped
+      if false
         var OneFunc: func
         var TwoFunc: func
         OneFunc = function('len')