[Bug Report] Incorrect locale in popconfirm component

### Element UI version
2.13.1

### OS/Browsers version
macOS / Google Chrome 81.0

### Vue version
2.6.11

### Reproduction Link
https://codepen.io/evgenij_/pen/VwvEMRG

### Steps to reproduce
Please use this Reproduction Link https://codesandbox.io/s/proud-moon-2cshd?file=/src/main.js instead of codepen

1. Click to the button - buttons lang is zh-CN instead of EN

### What is Expected?
EN locale is expected

### What is actually happening?
zh-CN is used for this component (popconfirm) even if i18n with en locale is used