It breaks for (foo in bar) severely:

[link|http://blog.metawrap.com/blog/CommentView,guid,42b961d5-b539-4d9a-b1e0-108e546ae3e6.aspx|http://blog.metawrap...108e546ae3e6.aspx]

1.4.0 does not have this issue; however, you have to get that version directly from the [link|http://dev.conio.net/repos/prototype/dist/|repository].