iOS 7-10 Safari: Long select options with flexbox parent overflow the page

## Summary:

Select options behave differently if the select element is a flex item. Long text in options will make the page overflow for no reason.
## Platforms:

iOS Safari 7 - 10
## How to reproduce:
1. Load the example
2. Swipe to the right
## Reduced Example:

[https://jsfiddle.net/zj1n06fp/6/](https://jsfiddle.net/zj1n06fp/6/)
## Workarounds:

Add `overflow-x: hidden` on the select element.
