Update esprima-fb

The latest versions of esprima-fb fix a large swath of issues and also align with the final ES6 modules spec. ES6 Module Transpiler, recast, ast-types etc have all made the move and while I see an interest in this project to move to acorn I think in the short term this upgrade would be very nice.

I am sure tests are broken, just opening this PR now in case there are objections in principal.