graphene:size-interpolate (a b factor result)

a -- a graphene:size-t instance
b -- a graphene:size-t instance
factor -- a number coerced to a double float with the linear interpolation factor
result -- a graphene:size-t instance for the interpolated size

The graphene:size-t instance with the interpolated size.

Linearly interpolates the components of a and b using the given factor.