Bug 263663

Created attachment 468335 [details]
Repro HTML

Relies on: https://bugs.webkit.org/show_bug.cgi?id=220719

Repro steps:

1. Go to https://codepen.io/nolanlawson-the-selector/pen/abXOKBO

Expected results:

The attributes `aria-braillelabel` and `aria-brailleroledescription` should reflect with the properties `ariaBrailleLabel` and `ariaBrailleRoleDescription` respectively.

Actual results:

The attributes do not reflect. Minimal repro:

```js
const elm = document.createElement('div');

elm.ariaBrailleLabel = 'foo'
elm.ariaBrailleRoleDescription = 'bar'

console.log('aria-braillelabel', elm.getAttribute('aria-braillelabel')) // should be 'foo'
console.log('aria-brailleroledescription', elm.getAttribute('aria-brailleroledescription'))  // should be 'bar'
```

In Safari Technology Preview 179 (Safari 17.0, WebKit 18617.1.8.1), these log `null` rather than `"foo"`/`"bar"` respectively.

ARIA PR: https://github.com/w3c/aria/pull/2057
WPT PR: https://github.com/web-platform-tests/wpt/pull/42751