AX: VoiceOver on Safari doesn't announce aria-live updates after uploading files. Works in Firefox.

• Component: Accessibility
• Status: NEW ---

[Claire Ryberg]

Created attachment 438350 [details]
Video showing VO not reading aria-live updates on Safari, but working correctly on Firefox

Summary:
When the onChange callback on an <input type="file"> element updates text within an aria-live="assertive" region, that text is not announced by VoiceOver.
Other text updates to the same aria-live region ARE announced by VoiceOver.


Steps to Reproduce:
Please use this CodeSandbox as an example: https://codesandbox.io/s/aria-live-with-file-upload-input-o00c7
Attached is a video of it not working on Safari and then working on Firefox

1. Turn on VoiceOver
2. Navigate to the "Choose file" button and select it
3. Select a file to upload
4. When the file selection dialog closes, see that text appears in the assertive aria-live region
5. Navigate to the "Trigger a live message" button and select it
6. See that updated text appears in the assertive aria-live region


Expected Results:
- Any text that is added to an assertive aria-live should be announced by VoiceOver
- Text added to the aria-live by an onChange callback on an <input type="file"> should be announced
- Text added to the aria-live by normal button triggers should be announced


Actual Results:
- Works as expected on Firefox v92.0 
- Works as expected on Safari iOS v14.7.1
- On Safari v14.1.2 macOS: Text added to the aria-live by an onChange callback on an <input type="file"> is NOT announced.
- On Safari v14.1.2 macOS: Text added to the aria-live by normal button triggers IS announced as expected
- On Chrome v93.0.45: same as Safari macOS


I discovered this bug while implementing a FileUpload component and trying to notify users of status updates, such as error or success messages. Without awareness of these updates, users of assistive technology are at a disadvantage as they are not easily made aware of things like upload failures or if their form is ready for submission.

[Radar WebKit Bug Importer]

<rdar://problem/83197224>