digits.t-mobile.com - Safari is not a recommended browser

[Karl Dubost]

This is happening for both Firefox and Safari.

This was reported initially to https://github.com/webcompat/web-bugs/issues/119767
Firefox https://bugzilla.mozilla.org/show_bug.cgi?id=1898952
Safari this issue.

The diagnosis is

```js
t.supportBrowser = function () {
      if (c()) return !0;
      if (r && !r.mobile) {
        const e = r.brands;
        if (e.length > 0) for (const t of e) if (['Google Chrome',
        'Microsoft Edge'].includes(t.brand)) return !0
      }
      return !1
    },
```

which relies on the support for Client Hints.

```
const r = navigator.userAgentData;
```

Firefox created a site intervention Quirk to provide an object for the site. 
https://github.com/mozilla-extensions/webcompat-addon/pull/362/files#diff-edfea982a0178b7a37361cb10b82f2fa16a793a3aaddabe651627aea35e8024d

[Radar WebKit Bug Importer]

<rdar://problem/132309517>