Keybase Chat injected button fails on Facebook profiles without username

Facebook users can exist without usernames, and in this case, their profile links are shown as below

```
https://www.facebook.com/profile.php?id=x
```

where `x` is their user ID. On these pages, interacting with an injected "Keybase Chat" button will intend to send communications to `profile.php@facebook`, as shown below.


Reproduce the injected Keybase Chat button on a Facebook profile URL using the profile.php?id=x form, then trace the profile parsing and recipient-building entry point. Confirm the behavior against a Facebook profile with a username as well, and consider the issue done when both forms identify the intended Facebook recipient rather than profile.php@facebook.

Written by the indexing model from the issue text.