Load <http://www.economist.com/> and hover over the left column, the menus that appear will be completely horizontal instead of stacked vertically.
Regression from Safari 3.1.1.
Created attachment 22040 [details]
First attempt at a reduction
This isn't really a reduction yet, but it removes the extraneous content and most of the scripting. I'll work on the CSS next.
Created attachment 22041 [details]
Here's a reduction. If I change the class of the <li> in the source itself instead of via an event handler, it works fine.
Works: r31872 Fails: r31878
Making <http://trac.webkit.org/changeset/31876> the prime suspect.
Fixed in <http://trac.webkit.org/changeset/36082>.