A decent idea of course, but you are going to run in to the same issue as everybody else who tries that: unless Firefox has a significant market share, it is just not worth throwing resources after it.
What you can do is develop automatic filters to make chrome specific CSS prefixes general, etc. Those are probably worth using since a few hours/days of engineering time easily is worth the larger market share.
Firefox already implements a bunch of -webkit prefixed features for compatibility reasons. Are there specific Chrome-only features that aren't yet supported that you think should be? If so, file Firefox bugs!
