Fixed error when parsing identifiers that start with keywords (e.g. staticMove)

Fixes error parsing [three-trackballcontrols.d.ts](https://github.com/borisyankov/DefinitelyTyped/blob/master/threejs/three-trackballcontrols.d.ts)
Verified that all other definition files  in [DefinitelyTyped](https://github.com/borisyankov/DefinitelyTyped) continue to be parsed correctly.