* A variant of a language has its own locale, for example the locale of the formal variant of German is `de_DE_formal`.
* Update `remove_accents()` and some CSS rules to support `de_DE_formal`.
* Add tests for `get_bloginfo( 'language' )`.
* API changes will be deployed over the next few days.
see #28303.
git-svn-id: https://develop.svn.wordpress.org/trunk@33027 602fd350-edb4-49c9-b593-d223f7449a82