distance and max: default values/ nullable

[riju]

@dontcallmedom raised the issue if we would prefer them to be nullable or assign default values (+Infinity).
Previous version of the spec had, distance and max, set to default as +Infinity. I initially had them null as on some platforms like Mac distance and max are both not retrievable using public API.

[riju]

I think making both distance and max non-nullable and making them default to +Infinity is better.
On platforms like Mac, where there is no way to retrieve distance and max, default value should be used. It might be better not to leak platform information this way.