Called before the given before and after states are compared.
The implementation can use this method to initialize any internal
state needed for processing the results of the comparison. For example
an implementation could look up the effective node type of the after
state to know what constraints to apply to on the content changes.
Called after the given before and after states are compared.
The implementation can use this method to post-process information
collected during the content diff. For example an implementation that
during the diff just recorded the fact that this node was modified
in some way could then use this method to trigger an index update
based on that modification flag.