deps/v8/src/js/array.js
function ArrayIncludes(searchElement, fromIndex) {
  CHECK_OBJECT_COERCIBLE(this, "Array.prototype.includes");

  var array = TO_OBJECT(this);
  var length = TO_LENGTH(array.length);

  return InnerArrayIncludes(searchElement, fromIndex, array, length);
}
function ArrayIncludes(searchElement, fromIndex) {
  CHECK_OBJECT_COERCIBLE(this, "Array.prototype.includes");

  var array = TO_OBJECT(this);
  var length = TO_LENGTH(array.length);

  return InnerArrayIncludes(searchElement, fromIndex, array, length);
}
ES2016 draft, section 22.1.3.11