fixed scroll in Firefox with scrollDistance = 0

For some reasons in Firefox on Mac `remaining` value in the end of the window equal 0.066650390625 or similar
So that's why, when `scrollDistance = 0` scroll do not trigger scroll function because (0.066650390625 > 0)

I think this is related to [this](https://github.com/BinaryMuse/ngInfiniteScroll/issues/24)