Instant Search: arrow is missing from sort dropdown on Safari

### Impacted plugin

Jetpack

### Steps to Reproduce

1. On a site with Instant Search enabled, perform a search in Safari with the product layout (`/?s=&result_format=product` will do it).

### A clear and concise description of what you expected to happen.

The sort dropdown looks like a dropdown.

### What actually happened

The sort dropdown still works, but looks like a text input. The arrow is missing from the right hand side.

### Other information

### Operating System

_No response_

### OS Version

_No response_

### Browser

Safari

### Browser Version(s)

_No response_

Reproduce the Instant Search product layout at /?s=&result_format=product in Safari and inspect the sort dropdown behavior. Done means the control still works and visibly retains a dropdown arrow on the right instead of appearing like a text input.

Written by the indexing model from the issue text.