[Bug Report] Opened colorpicker scroll issue

### Element UI version
2.13.0

### OS/Browsers version
win/chrome

### Vue version
2.6.11

### Reproduction Link
https://jsfiddle.net/ot84ewhc/

### Steps to reproduce
- Open colorpicker
- Scroll while colorpicker opened

Issue can be reproduce on official Element UI component documentation. Open color picker and scroll:
https://element.eleme.io/#/en-US/component/color-picker

It even goes over top nav,

### What is Expected?
- Overflow to be hidden or colorpicker to be closed on scroll so it does not cover other elements on page

### What is actually happening?
-When scrolling with opened colorpicker it covers other elements