Bug 1026328 - [Settings] Also set the l10nId to the tone buttons

We may not have `tonename.l10nID` at the moment, can we mix the check on L229 to to make sure we have tonename.l10nID ?

Here comes a sample : 

```javascript
var l10nID = tonename && tonename.l10nID;
var name = l10nID ? _(l10nID) : tonename;

toneType.button.textContent = name || _('change');
toneType.button.dataset.l10nId = l10nID || '';
```