[bug]g2-brush无法选中右半边的条柱

[ahuigo]

试了chrome & safari ，发现无法选中右半边的条柱.

• demo为：

https://bizcharts.net/products/bizCharts/demo/detail?id=g2-brush-interval&selectedKey=概览

https://codepen.io/ahuigo/pen/jOEKmxp?editors=1010