function numberToSplitLong(num) {
    if (typeof num !== 'number') {
        return [0, 0];
    }
    return [num | 0, (num / UPPER_BIT_DIVISOR) | 0];
}
Convert a JS double-precision floating point number to a split long
@private
@param  {number} num  Number to convert
@return {SplitLong}     A two-element array with 32 lower bits and 32 upper bits