Display lists used to own the resource storage needed to replay their
command bytes. That kept the compositor tied to in-process object
ownership: sending a display list update also meant sharing the same
resource container with the recording side.
Move resource storage out of DisplayList and make display list updates
carry a transaction of resources to add and remove. Navigable now tracks
the resources referenced by the current display list, sends only the
delta to the compositor, and trims its recording-side storage to the
active set. The compositor applies those transactions to its own storage
before replacing the cached display list.
This still carries in-process resource objects, but it puts the
ownership boundary in the right place. Command bytes and resource
lifetime are now synchronized explicitly, which is the shape needed
before the compositor can receive serializable resource updates across a
process boundary.