twbs/bootstrap — pull request #13664 by mckramer (2014-05-22 22:22:13+00:00)
Title: Add aria-haspopup and aria-expanded attributes to dropdown plugin

1. Add aria-haspopup="true" and aria-expanded="false" to dropdown docs
2. Toggle aria-expanded between "true" and "false" when opening and closing dropdown

Satisfy item 1 from https://github.com/paypal/bootstrap-accessibility-plugin#dropdown. See #13553.