Fixed problems when building using Google Closure

Returned structure with quoted elements, this is a no-no in Closure:

<BAD>
     return { "start": start,
     "end": index,
     "next": index + 1,
     "string": s.join('') };
</BAD>

<GOOD>
     return { start: start,
       end: index,
       next: index + 1,
       parsedString: s.join('') };
</GOOD>