patch 8.0.1377: cannot call a dict function in autoloaded dict

Problem:    Cannot call a dict function in autoloaded dict.
Solution:   Call get_lval() passing the read-only flag.
diff --git a/src/testdir/sautest/autoload/foo.vim b/src/testdir/sautest/autoload/foo.vim
new file mode 100644
index 0000000..d7dcd5c
--- /dev/null
+++ b/src/testdir/sautest/autoload/foo.vim
@@ -0,0 +1,7 @@
+let g:loaded_foo_vim += 1
+
+let foo#bar = {}
+
+func foo#bar.echo()
+  let g:called_foo_bar_echo += 1
+endfunc