Can you please fix the tests to include the new data attribute?
Also, data-lang vs data-language? What do you think?
lang is used in other places, such as <html lang='en'>, so I think I prefer data-lang for consistency with that.
👍 to consistency with lang.
Add a `data-lang` attribute to code blocks
@benbalter Will bring this in tomorrow as well, which might break your tests again. Just a head's up :)
Update history to reflect merge of #1066.