[uievents] Clarify expected DomKey for Ctrl+Alt+c on Android with default layout (#77)

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.

Android doesn't have `AltGr` but sometimes `Alt+foo` will produce a character, for example `Alt+c` (AltLeft or AltRight) will produce `ç` on default layout.

So should `Ctrl+Alt+c` produce `c` or `ç` (consider `Alt` as `AltGr` in this case)?

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Reply to this email directly or view it on GitHub:
https://github.com/w3c/uievents/issues/77