patch 8.2.3705: cannot pass a lambda name to function() or funcref()

Problem:    Cannot pass a lambda name to function() or funcref(). (Yegappan
            Lakshmanan)
Solution:   Handle a lambda name differently.
diff --git a/src/testdir/test_expr.vim b/src/testdir/test_expr.vim
index 323ce26..46d7186 100644
--- a/src/testdir/test_expr.vim
+++ b/src/testdir/test_expr.vim
@@ -547,6 +547,13 @@
   call assert_fails("call function('foo()')", 'E475:')
   call assert_fails("call function('foo()')", 'foo()')
   call assert_fails("function('')", 'E129:')
+
+  let Len = {s -> strlen(s)}
+  call assert_equal(6, Len('foobar'))
+  let name = string(Len)
+  " can evaluate "function('<lambda>99')"
+  call execute('let Ref = ' .. name)
+  call assert_equal(4, Ref('text'))
 endfunc
 
 func Test_funcref()