Header's getting an undefined class

[tybenz]

When using firebug on the docs page, and inspecting the buttons in the radio and checkbox elements, the labels have a class of "ui-btn-up-undefined". And on the regular button, there is a class of "ui-btn-up-". It does not happen on the select, slider, or the toggle.

This is true for mini form elements and regular ones.

[toddparker]

That seems like an odd regression. We'll lok into this right away.