formatValues(keys) {
    return this.formatWithFallback(keys, valueFromBundle);
  }
Retrieve translations corresponding to the passed keys.

A generalized version of `DOMLocalization.formatValue`. Keys must
be `{id, args}` objects.

Returns a Promise resolving to an array of the translation strings.

@example
```js
docL10n.formatValues([
  {id: 'hello', args: { who: 'Mary' }},
  {id: 'hello', args: { who: 'John' }},
  {id: 'welcome'}
]).then(console.log);

// ['Hello, Mary!', 'Hello, John!', 'Welcome!']
```

@param   {Array<Object>} keys
@returns {Promise<Array<string>>}