Can we remove UUID since Worker code is removed?

[tbranyen]

In the spirit of trimming down as much as possible in here, I think the UUID logic isn't necessary anymore. We retain descriptor objects in memory so a WeakMap would work perfectly to align descriptors with real elements.

[tbranyen]

This is going to be repurposed to detect if content is "static" or "dynamic". If the UUIDs do not change, then it will not check for any changes and simply iterate down to the children.