Hello world!

1. When the elements are created, two slotchange events are dispatched. The first slotchange is for green-frame#one. This is triggered by the text node "Hello world!" being transposed into the green-frame slot. The second slotchange is triggered by the slot node with the fallback text node "Hello sunshine!" being transposed into the green-frame#three slot. But, if no transposed nodes are passed at startup, and the slot inside green-frame uses its "¯\_(ツ)_/¯" fallback text node, then _NO_ slotchange event will trigger.
2. After 1000ms the "Hello world!" text node is removed from green-frame#one. This causes the list of transposed nodes to change to empty, and this triggers the third slotchange event. This means that slotchange events will be triggered every time a slot falls back to its fallback nodes _after_ a node has first been transposed into it. The _only_ time a slotchange event does _not_ occur for a change in the displayed content of a slot in the flattened DOM is when a slot uses its initial fallback nodes.