public/javascript/libs/select2.js
function (delta) {
            var choices = this.findHighlightableChoices(),
                index = this.highlight();

            while (index > -1 && index < choices.length) {
                index += delta;
                var choice = $(choices[index]);
                if (choice.hasClass("select2-result-selectable") && !choice.hasClass("select2-disabled") && !choice.hasClass("select2-selected")) {
                    this.highlight(index);
                    break;
                }
            }
        }
function (delta) {
            var choices = this.findHighlightableChoices(),
                index = this.highlight();

            while (index > -1 && index < choices.length) {
                index += delta;
                var choice = $(choices[index]);
                if (choice.hasClass("select2-result-selectable") && !choice.hasClass("select2-disabled") && !choice.hasClass("select2-selected")) {
                    this.highlight(index);
                    break;
                }
            }
        }
abstract