I think Chrome does this as well. The real problem is that it doesn't seem to work with dynamically created forms, and web devs ruined everything with client-side templating.

But along the same lines, I would like it if browsers waited 5 seconds before actually killing a tab that you closed. That would not only fix your problem (if you applied it to page history changes as well), but solve most accidental data loss problems, and most importantly for me, be the end to having to reload entire pages just because I held down Ctrl-W for too long.