Regexp tokens are out of order (this shows the error not the fix)

This is not present in upstream esprima (looks like this was forked from the harmony branch which has some ... uh issues).

Digging through some code I suspect this is the fix: https://github.com/ariya/esprima/commit/32ba2a27e65e8e7b6dd50cb843206ff00693c222

As it stands if your relying on the token ordering your going to have a bad time with regexp inside of an object (maybe other things as well)