_deliverQueue(dq) {
        const listeners = dq.current._listeners;
        while (dq.i < dq.end) {
            // important: dq.i is incremented before calling deliver() because it might reenter deliverQueue()
            this._deliver(listeners[dq.i++], dq.value);
        }
        dq.reset();
    }
Delivers items in the queue. Assumes the queue is ready to go.