SlexAxton/messageformat.js — pull request #4 by Stuk (2012-05-04 22:23:48+00:00)
Title: Add MessageFormat.fallback and use it to find the pluralFunc

When no pluralFunc is found for the given locale we remove the
last tag from the locale and try again until there are no tags
left. The tags can be separated by either "-" (dash) or "_"
(underscore).

For example:
```
en_US -> no match
en -> match

zh-yue-Hant-HK -> no match
zh-yue-Hant -> no match
zh-yue -> no match
zh -> match (if locale/zh.js has been loaded)
```
If no match can be found then a Error is thrown.