patch 8.2.4225: Vim9: depth argument of :lockvar not parsed in :def function

Problem:    Vim9: depth argument of :lockvar not parsed in :def function.
Solution:   Parse the optional depth argument. (closes #9629)
            Fix that locking doesn't work for a non-materialize list.
diff --git a/src/testdir/test_vim9_disassemble.vim b/src/testdir/test_vim9_disassemble.vim
index 8731052..d333090 100644
--- a/src/testdir/test_vim9_disassemble.vim
+++ b/src/testdir/test_vim9_disassemble.vim
@@ -625,7 +625,7 @@
         '\d STORE $0\_s*' ..
         'lockvar d.a\_s*' ..
         '\d LOAD $0\_s*' ..
-        '\d LOCKUNLOCK lockvar d.a\_s*',
+        '\d LOCKUNLOCK lockvar 2 d.a\_s*',
         res)
 enddef