twitter/bootstrap — pull request #5786 by cvrebert (2012-11-05 02:40:21+00:00)
Title: fixes #5494: style invalid fields as invalid regardless of required-ness

The obvious, simple fix for #5494. Removes the `:required` selectors from the `:invalid` styles so that optional fields with invalid values also get styled.

The commit which originally introduced these styles (1209a375) does not explain the inclusion of the `required`s, nor does the blog post to which it links (said post instead justifies the `:focus`es), so the exclusion of optional fields doesn't seem to have been deliberate / explicitly-intended.