Handling localized dates is tricky it requires specific l10n resources (= `shared/locales/date.ini`). That’s why it’s not supported “natively” by `l10n.js` yet, I don’t want this library to depend on any external l10n resources.

I don’t think we could include the code above in `l10n.js`: the `date` argument might be already used, or we could have several dates to handle in the same HTML element (e.g. “from monday, 10AM to friday, 2PM”), etc. 

Maybe this code could live in `l10n_date.js` but I don’t really know what a generic solution would look like. The `data-l10n-date` and `data-l10n-date-format` attributes are a good idea for handling a single date per element, but doesn’t work for several dates.

Since I have nothing really better/generic to propose, I’m fine with the proposed patch. If you can think of a generic way to support these dates, I’ll be happy to implement it (or review a patch) as long as it does not make `l10n.js` dependent of an external l10n resource like `shared/locales/date.ini`.