[uievents] Clarify expected DomKey for Shift+AltGr+0 on Windows with fr-FR layout (#78)

The spec currently says

> ...the key value should be the printable key value that would have been produced if the key had been 
> typed with the default keyboard layout with no modifier keys except for 'Shift' and 'AltGr' applied.

On Windows fr-FR layout pressing `0` produces `à`, `Shift+0` produces `0`, `AltGr+0` produces `@`, but `Shift+AltGr+0` does't produce printable character. So should it be `Unidentified` or one of the above keys?

Another question, on Windows fr-FR layout `AltGr+foo` does not always produce a printable character (e.g. `AltGr+j`), so should the DomKey be `Unidentified` or `j`?



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Reply to this email directly or view it on GitHub:
https://github.com/w3c/uievents/issues/78