These classes were renamed in T393867. Extensions using the old aliases and event type strings should be updated.
I also noticed some core classes still referencing the old names.
- Update core code that "extends PageStateEvent" or uses "PageStateEvent", PageRevisionUpdatedEvent, "PageRevisionUpdated", or $pageRevisionUpdatedEvent field
- Possibly add *Listener interfaces to extensions to verify the name is right
- Update extensions likewise