Toggleable navbars do not transition on collapse

Created by: davidjb

Looking at the v4 documentation page for Navbars (http://v4-alpha.getbootstrap.com/components/navbar/#collapsible-content), the first collapsible content example smoothly transitions on close, but the responsive navbar (second example) collapses immediately without a transition.

Example showing with and without a clearfix: http://codepen.io/davidjb/full/NxvxGe/

The issue (assuming unintentional) appears to be related to the floats within the .collapse element. With only floated elements inside (eg .navbar-brand and .nav-item), the transition occurs on open, but not on close. By adding something like a .clearfix to the collapse navbar-toggeable-*, the issue is worked around.

The same results are seen in my testing under Firefox 45a2 and Chromium 47.0.2526.73 on Ubuntu 15.10.