= Back / Forward Cache
''by Chris Dumez''

- Objectives
    - Make pages suspendable most of the time (~98%)
    - Allow for much faster back/forward navigation
    - Means addressing most failures to suspend, not introducing new ones
- ActiveDOMObject
    - Largest cause of failures
    - Need to drop all shouldPreventEnteringBackForwardCache_DEPRECATED() overrides
    - Queue tasks on the event loop for running script (e.g. event dispatch, promise resolution)
    - Pause CPU-intensive work (e.g. animations) in suspend() and unpause it in resume() 
    - Abort work that cannot be paused in suspend() and make sure tasks to dispatch relevant error events are queued on the event loop 
- Dedicated Workers
    - Dedicated workers have their whole thread suspended when entering the back/forward cache
    - ActiveDOMObject::suspend() / resume() do not get called
- Service Workers
    - Service workers cannot be easily suspended because they can be shared
    - When a client page goes into the back/forward cache, it gets disconnected as a client of the service worker
    - When a service worker no longer has any clients, it is terminated