function map(array, fn) {
	var result = [];
	var length = array.length;
	while (length--) {
		result[length] = fn(array[length]);
	}
	return result;
}
A generic `Array#map` utility function.
@private
@param {Array} array The array to iterate over.
@param {Function} callback The function that gets called for every array
item.
@returns {Array} A new array of values returned by the callback function.