Add support for ES6 / Firefox 44

[PerfectSlayer]

Firefox 44 brings Ecmascript 6 support and include some breaking changes.
For more details, check the blog post about this topic.

The extension is affected (for example, no more translation due to code like:

// Context Menu
const LABEL_LOADING = 'Fetching translation…'
const LABEL_TRANSLATE = 'Translate “{0}”'
const LABEL_TRANSLATE_PAGE = 'Translate Page ({0} > {1})'
const LABEL_CHANGE_LANGUAGES = 'Change Languages ({0} > {1})'

This issue is a tracking issue for the Firefox 44 support.

[bpierre]

The issue with the format() function should be fixed since that commit: 9f17b44

Is this the issue you are talking about?

[PerfectSlayer]

My bad... It seems I stay on one of my outdated feature branches. Seems to work fine with Firefox 44 😉

[bpierre]

👍