页面整体缩放后，echarts的鼠标会很不正常

### Version
4.2.1

### Steps to reproduce

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### What is expected?
请注意body中的style属性，zoom:0.5
希望页面整体缩放后，当鼠标移到echarts上后，鼠标指示的是真实的echarts图像位置

### What is actually happening?
页面整体缩放后，当鼠标移到echarts上后，会发现鼠标指针和实际echarts标示的位置不一致

No source file, test, or entry point is named in the report. Start by reproducing the issue with body zoom:0.5 and a line chart, then trace ECharts' mouse-position handling; done means the pointer and chart-marked position remain aligned after page zoom.

Written by the indexing model from the issue text.