data-expands throws off css related to child counts

[ccomparini]

Because data-expands hides the prototype element instead of removing it from the tree, the prototype element remains a child of its parent, which throws off css selectors like :last-child.

See the example in the embedded css here.

[ccomparini]

This may be hard to fix because if the prototype element is removed from the parent, there's no reference for where to insert the clones for that prototype.

One possible solution would be to track the original previousElementSibling (or nextElementSibling) in the prototype and use that to determine the location to insert clones. But then, what happens if there are 2 expansions within one parent element, one directly after the other? Ahh - perhaps the parent could keep a map of [next sibling] -> prototype, and, when we recurse on children, if that child is in the map, then recurse on the prototype first. A little complicated, but might work.