How to use the es-abstract/es6.ToInteger function in es-abstract

var atShim = function at(pos) {
	ES.RequireObjectCoercible(this);
	var O = ES.ToObject(this);
	var S = ES.ToString(O);
	var position = ES.ToInteger(pos);
	var size = S.length;
	if (position < 0 || position >= size) {
		return '';
	}
	// Get the first code unit and code unit value
	var cuFirst = S.charCodeAt(position);
	var cuSecond;
	var nextIndex = position + 1;
	var len = 1;
	// Check if it’s the start of a surrogate pair.
	var isHighSurrogate = cuFirst >= 0xD800 && cuFirst <= 0xDBFF;
	if (isHighSurrogate && size > nextIndex /* there is a next code unit */) {
		cuSecond = S.charCodeAt(nextIndex);
		if (cuSecond >= 0xDC00 && cuSecond <= 0xDFFF) { // low surrogate
			len = 2;
		}

module.exports = function includes(searchElement) {
	var fromIndex = arguments.length > 1 ? ES.ToInteger(arguments[1]) : 0;
	if (indexOf && !$isNaN(searchElement) && $isFinite(fromIndex) && typeof searchElement !== 'undefined') {
		return indexOf.apply(this, arguments) > -1;
	}

	var O = ES.ToObject(this);
	var length = ES.ToLength(O.length);
	if (length === 0) {
		return false;
	}
	var k = fromIndex >= 0 ? fromIndex : Math.max(0, length + fromIndex);
	while (k < length) {
		if (ES.SameValueZero(searchElement, O[k])) {
			return true;
		}
		k += 1;
	}