A TransparentContainer node is an object intended to be used as a primitive in templating systems. It's effectively a DocumentFragment node that is not "unwrapped" upon insertion. TransparentContainer nodes can be arbitrarily nested.
Selector matching and rendering will act as if any TransparentContainer nodes in the node tree are replaced by their contents.
Hierarchy restrictions placed upon nodes will need to apply to the children of TransparentContainer nodes as if the TransparentContainer node was not there. We can simplify these requirements somewhat by only allowing TransparentContainer nodes as descendants of the root element.
[Constructor,
Exposed=Window]
interface TransparentContainer : Node {