Iterator resizing is not recorded in history

[RunDevelopment]

You can't undo resizing an iterator.

Steps to reproduce:

1. Create an iterator node.
2. Fill it with nodes.
3. Resize the iterator such that it is smaller and has to rearrange its children to fit.
4. Ctrl+Z.

[joeyballentine]

I feel like this will be something easier to address once you refactor global state

[theflyingzamboni]

Or irrelevant once iterators are reworked haha.