条形图在加入Pan手势且canvas不在(0, 0)的情况，触摸点位置不正确

- [x] I have searched the [issues](https://github.com/antvis/f2/issues) of this repository and believe that this is not a duplicate.

### Reproduction link
[https://antv.alipay.com/zh-cn/f2/3.x/demo/interaction/pan-for-line-chart.html](https://antv.alipay.com/zh-cn/f2/3.x/demo/interaction/pan-for-line-chart.html)

### Steps to reproduce
##### 1.打开demo链接：https://antv.alipay.com/zh-cn/f2/3.x/demo/interaction/pan-for-line-chart.html
##### 2.用下面代码替换模版全部代码：

```javascript

F2 图表组件库 - AntV

/*Fixing iframe window.innerHeight 0 issue in Safari*/document.body.clientHeight;

$.getJSON('https://gw.alipayobjects.com/os/antvdemo/assets/data/f2/linear-pan.json', function(data) {
var chart = new F2.Chart({
id: 'mountNode',
pixelRatio: window.devicePixelRatio
});
chart.source(data, {
release: {
min: 1990,
max: 2010
}
});
chart.tooltip({
showCrosshairs: true,
showItemMarker: false,
background: {
radius: 2,
fill: '#1890FF',
padding: [3, 5]
},
nameStyle: {
fill: '#fff'
},
onShow: function onShow(ev) {
var items = ev.items;
items[0].name = items[0].title;
}
});
chart.interval().position('release*count');
chart.interaction('pan');
chart.scrollBar({
mode: 'x',
xStyle: {
offsetY: -5
}
});
chart.coord({
transposed: true
});

// 绘制 tag
chart.guide().tag({
position: [1969, 1344],
withPoint: false,
content: '1,344',
limitInPlot: true,
offsetX: 5,
direct: 'cr'
});
chart.render();
});

```

### What is expected?
触摸点是正确的，选中手指位置的数据

### What is actually happening?
触摸点向下偏移，偏移量为canvas的y值

| Environment | Info |
|---|---|
| f2 | 3.4.2 |
| System | Mac 10.15 |
| Browser | Chrome 77.0.3865.90 |

Start with the linked pan-for-line-chart reproduction and inspect F2's pan interaction handling for touch coordinates when the canvas has a nonzero page offset. Reproduce the downward offset with the provided example, then verify that touching a bar selects the data at the finger position even when the canvas is below the page origin.

Written by the indexing model from the issue text.