vdom.Helper: createDeltas() => removeAll OP

The following conditions need to be true:

1. The new vnode.childNodes array must be empty
2. The oldVnode.childNodes array must have more than one item
3. None of the oldVnode.childNodes items does exist inside the new vnode tree (map check)

If all 3 conditions match, we can replace all single removeNode deltas with a single removeAll delta.

To do this, we need to store all remove deltas of the current method call (non-recursively) and replace them as needed.