line-stack value in Y column not right

[FeiyunWu]

• I am using English in this issue. 在这个 Issue 中我使用了英文（强烈建议）。

General Questions

• Required: I have read the document and examples and tried to solve it by myself. （必填）我读过了文档和教程，并且曾试图自己解决问题。
• Required: I have searched for similar issues and that didn't help. （必填）我搜索过 issue 但是没有帮助。
• Required: I have tried with the latest version of ECharts and still have this problem. （必填）我试过最新版本的 ECharts，还是存在这个问题。

In this issue, I have provided information with: 在这个 issue 中我提供了以下信息：

• Required: issue type；（必填）issue 类型
  line-stack Chart value not right

• Required: one sentence description in issue details；（必填）一句话的问题描述
  As the snap-shot,the value should be **182,**not 300+.
  

• Required: demo；（必填）能反映问题的例子（如果你想提问或报 bug）
  1.Open linke http://echarts.baidu.com/examples/editor.html?c=line-stack
  2.You will find the numbers are not right .

• Required: ECharts version；ECharts 版本

Issue Type

• I have a question to ask about how to use ECharts to ...；我想提问如何使用 ECharts 实现某功能
• I have a bug to report；我想要报 bug
• I have a feature to request, e.g.: I'd like a new feature that ...；我需要一个新功能
• I have a feature to enhance, e.g.: The current feature should be improved in the way that ...；我希望改进某个功能
• There's something wrong with the documents；文档有些问题
• Others, or I'm not sure which issue types to choose here；其他，或我不知道应该选什么类型

Issue Details

Expected Behavior

Current Behavior

Online Example

Topics

• Legend
• Tooltip
• Event
• Performance
• SVG
• Map
• ECharts GL
• Third-party libraries, e.g.: Vue.js, React

Anything Else We Need to Know

Environment

• ECharts version；ECharts 版本: {DESCRIBE_HERE}

• It happens only on certain browsers or operating systems. 对于特定浏览器或操作系统才会出现的问题，请提供相应环境信息：{BROWSER_VERSION_OR_OS_INFORMATION_HERE}

[cuijian-dexter]

you can set series[0].data = [{value:1},{value:2}]

[cuijian-dexter]

@FeiyunWu What you're demonstrating is that each broken line is based on the position accumulated from the previous data.