Use the updated module export declaration syntax.

https://code.google.com/p/esprima/issues/detail?id=410
Use the updated module declaration syntax.

https://code.google.com/p/esprima/issues/detail?id=410
Obey automatic semicolon for export default.

https://code.google.com/p/esprima/issues/detail?id=410
Only allow export declaration inside a module body.

https://code.google.com/p/esprima/issues/detail?id=410