Missing form-item class for node entry page

While using the Admin module, I noticed that any Date Popup field renders with odd padding and margins. I narrowed it down to a missing 'form-item' class. Adding this additional class to the wrapper div solves the problem. It should improve the appearance of the Date Popup field within any theme that makes use of form-item as a container.

I've attached a screenshot for reference, as well as a patch.