79a9e670a2
This also changes the way we insert nodes into a MultiChildRenderObjectWrapper's renderObject, which fixes issue #626. Now, instead of the slot being a renderObject, it's the Widget that currently uses that renderObject. That way when the Widget changes which renderObject to use, the siblings of that Widget in the same child list don't have to be notified of the change. I tested performance of the new algorithm vs the old algorithm using the stocks demo at idle and the stocks demo scrolling steadily. The data suggests the algorithms are roughly equivalent in performance.