function repeatWhen(notifier) {
    return function (source) { return source.lift(new RepeatWhenOperator(notifier)); };
}
Promisifies all the selected functions in an object and backward compatible with callback.

@param {Object} source the source object for the async functions
@param {Object} [destination] the destination to set all the promisified methods
@param {Array} [methods] an array of method names of `source`
@return {Object}
@api public