html.elements.select - various outdated notes

What information was incorrect, unhelpful, or incomplete?

1. Chrome, Webview Android, Chrome Android, and Samsung Internet have an outdated note about border-radius which at some point has become no longer relevant to Blink browsers.

2. WebView Android also has another note that is almost definitely no longer relevant
   

3. Firefox has a note that is potentially no longer relevant (see also https://github.com/mdn/browser-compat-data/issues/12592 Point 1 for a similar/identical note.
   

4. Firefox Android has a note about background-image that I believe is no longer relevant.
   

What did you expect to see?

No longer relevant notes removed.

Did you test this? If so, how?

1. Tested in Chrome and Safari (both on desktop) by adding a border-radius in dev tools.

2. No.

3. No.

4. Loaded a select multi in Firefox android and didn't see anything odd with the input.

Can you link to any release notes, bugs, pull requests, or MDN pages related to this?

https://developer.mozilla.org/en-US/docs/Web/HTML/Element/select

Review html/elements/select.json and the linked MDN select documentation first. Check whether each listed browser note still applies, using the browser cases described in the issue where needed. Done means the outdated notes are removed while any still-relevant compatibility notes remain.