Corrected type annotations and method signatures for ZyngaScroller

Corrected wrong types (number -> boolean, boolean -> number).
Added missing callback argument.

See:
[zynga/scroller L443](https://github.com/zynga/scroller/blob/dadd850722ad2be9a865e4d84cb76c0197b68734/src/Scroller.js#L443)
[zynga/scroller L512](https://github.com/zynga/scroller/blob/dadd850722ad2be9a865e4d84cb76c0197b68734/src/Scroller.js#L512)
[zynga/scroller L529](https://github.com/zynga/scroller/blob/dadd850722ad2be9a865e4d84cb76c0197b68734/src/Scroller.js#L529)
[zynga/scroller L610](https://github.com/zynga/scroller/blob/dadd850722ad2be9a865e4d84cb76c0197b68734/src/Scroller.js#L610)