As of 08ae388, `_getLabelFromNode` has been split into two different methods now.  One [returning HTML](https://github.com/derek/yui3/blob/08ae388bc1e48d8f67a1528cc4574d2373bd533d/src/button/js/core.js#L370) and the other [returning a String](https://github.com/derek/yui3/blob/08ae388bc1e48d8f67a1528cc4574d2373bd533d/src/button/js/core.js#L353).