AUI-1039 - Hovering over an ToggleButton in a ToolBar causes the icon to disappear

Hi Jon,

Attached is an update for https://issues.liferay.com/browse/AUI-1039.

This issue only occurs on 2.0.x because of changes to YUI's button-core that are in 2.5.x and master.

Please let me know if there are any issues.

Thanks!