Function taskComplete

public/javascripts/async.js:541–546

()

            if (idx >= 0) listeners.splice(idx, 1);
        }
        function taskComplete() {
            remainingTasks--;
            _arrayEach(listeners.slice(0), function (fn) {
                fn();
            });
        }

        addListener(function () {
            if (!remainingTasks) {