timelinechanged事件currentIndex问题

[fallowu]

问题简述 (One-line summary)

版本及环境 (Version & Environment)

• ECharts 版本 (ECharts version):3.2.3
• 浏览器类型和版本 (Browser version):Chrome 51.0
• 操作系统类型和版本 (OS Version): WINDOWS 10

重现步骤 (Steps to reproduce)

1.官方实例http://echarts.baidu.com/gallery/editor.html?c=doc-example/mix-timeline-all
2.添加时间轴timelinechanged事件监听
3.自动播放和点击时间点。
4.使用左右切换按钮

期望结果 (Expected behaviour)

currentIndex结果都为0-9，
实际结果为：
自动播放时为10,1,2,3,4,...,9
点击时间点时为,0,1,2,3,...,9
使用左切换按钮时为：-1,0,1,2,...,8

可能哪里有问题 (What went wrong)

            _changeTimeline: function (nextIndex) {
                var currentIndex = this.model.getCurrentIndex();

                if (nextIndex === '+') {
                    nextIndex = currentIndex + 1;
                }
                else if (nextIndex === '-') {
                    nextIndex = currentIndex - 1;
                }

                this.api.dispatchAction({
                    type: 'timelineChange',
                    currentIndex: nextIndex,
                    from: this.uid
                });
            }

ECharts配置项 (ECharts option)

option = {

}

其他信息 (Other comments)