[Bug Report] The example of pull up has bug in the iPhone browser, which will display the white screen

### Mint UI version
2.2.13

### OS/Browsers version
ios/all

### Vue version
2.5.13

### Reproduction Link
[https://elemefe.github.io/mint-ui/#/pull-up](https://elemefe.github.io/mint-ui/#/pull-up)

### Steps to reproduce
Copy https://elemefe.github.io/mint-ui/#/pull-up into the iPhone browser and slide up, there will be a white screen

### What is Expected?
Don't appear white screen

### What is actually happening?
There is a white screen