The widgets now extend the default core widget classes rather than the WP_Widget classes.  This allows us to take advantage of some stuff that's already built into core.
Make sure the taxonomy is an array.
Revert "The widgets now extend the default core widget classes rather than the WP_Widget classes.  This allows us to take advantage of some stuff that's already built into core."

This reverts commit b6a0cf65f7bb3b4e79be9dddb62f6ea69924f286.

Conflicts:
	inc/widget-tags.php