disconnect_() {
        // Do nothing if running in a non-browser environment or if listeners
        // have been already removed.
        if (!isBrowser || !this.connected_) {
            return;
        }

        document.removeEventListener('transitionend', this.onTransitionEnd_);
        window.removeEventListener('resize', this.refresh);

        if (this.mutationsObserver_) {
            this.mutationsObserver_.disconnect();
        }

        if (this.mutationEventsAdded_) {
            document.removeEventListener('DOMSubtreeModified', this.refresh);
        }

        this.mutationsObserver_ = null;
        this.mutationEventsAdded_ = false;
        this.connected_ = false;
    }
Removes DOM listeners.

@private
@returns {void}