Ref T2009. This is another almost-identical copy of the row scaffolding, which has the same 1up/2up bugs as the 8 other copies of this code.

Turn the "undo" element into an InlineCommentView so we can scaffold it.

Then, scaffold it with the same code as everything else.

Hit "Undo", swapped from 1up to 2up, hit "undo" again, swapped back, tried left/right, everything rendered with proper scaffolding.