Bug 1061120 - [Calllog][Dialer] Time duration format is not showing 'min...

...' or 's' in 'Call Information'
There's only two callsites for this function, and they both are of the form ```someHTMLElement.textContent = Utils.prettyDuration(/* ... */);``` This is an antiquated use of the l10n API as it doesn't respond to changes in the locale. Please file a followup to use l10n attributes instead and make it block the 'dialer-most-wanted' bug. It would look something like this:
```js
prettyDuration(node, duration, l10nIdPrefix) {
  var l10nId = l10nIdPrefix + /* do the body of the function */;
  node.dataset.l10nId = l10nId;
  node.dataset.l10nArgs = JSON.stringify(durationL10n);
}
```