View transitions specify that the image should be captured at the same size as in the document

Render element and its descendants, at the same size it appears in its node document, over an infinite transparent canvas, following the capture rendering characteristics.

It's unclear what to do if the element is fragmented. Is this supposed to capture the union of the fragment sizes/positions or something else?

I can't think of any good example where a developer would want to transition a fragmented element, so my proposal is to treat an element that is fragmented as invalid element to share in a view transition and skip the transition.