Missing first data point after moving datazoom in xAxis type time

### Version
5.0.2

### Reproduction link
[https://jsfiddle.net/](https://jsfiddle.net/)

### Steps to reproduce
After moving the datazoom, especially when moving it backward, the data displayed do not match the label in the datazoom handle and it also do not match the minimum label displayed in xAxis.

### What is expected?
It is expected that the first displayed date should be displayed in the chart as it is displayed in the xAxis and in the datazoom handle.

### What is actually happening?
The first data shown in the graph is not the corresponding to the first point in the xAxis or in the datazoom handle. It displays the next date.

Start with the reported ECharts 5.0.2 behavior for a time-type xAxis and the linked jsFiddle reproduction. Trace how moving the datazoom, especially backward, selects the first displayed point and aligns it with the xAxis minimum and datazoom handle labels. Done means the first plotted date matches both displayed labels after moving the datazoom.

Written by the indexing model from the issue text.