fails:Float#divmod returns an [quotient, modulus] from dividing self by other
fails:Float#divmod raises a FloatDomainError if self is NaN
fails:Float#divmod raises a FloatDomainError if other is NaN
fails:Float#divmod raises a FloatDomainError if self is Infinity
fails:Float#divmod raises a ZeroDivisionError if other is zero
fails:Float#divmod returns the correct [quotient, modulus] even for large quotient
