Pseudo-state as second element of `>`, `+`, and `~` combinators broken

[bencalabrese]

Heya, looks like a great add-on! I can't use it quite yet because some combinators are broken.

The following statement:

.parent > :focus { ... }

Tries to get rewritten, as:

 .pseudo-focus .parent > { ... }

which isn't valid CSS and blocks the rewritten sheet from being loaded.