mootools/mootools-core — pull request #2390 by cpojer (2012-07-31 14:26:06+00:00)
Title: Use the HTML5 classList API in supported browsers.

We are long overdue in supporting this API. The main reason we should add this is for perf: http://hacks.mozilla.org/2010/01/classlist-in-firefox-3-6/

Instead of changing the full className only a single class is being added/removed and engines can optimize for that.