Layer Tree Synchronizer can either do full tree sync or re-use layers by checking their ID.

Property tree sync now only does full tree sync. We need to enable re-use of info inside property tree nodes by looking at unique stable identifier, right now the identifier would be owning layer id. In the future it would use some stable element id.

For properties being animated, such as transform/opacity/filters, the most recent value need to be collected from old property trees and pushed to the new property trees.

For Render Surface, we need to pass ownership from old effect tree to new effect tree to keep damage and other info that lives on Render Surface.

For scrolling, this is already done by the ScrollOffsetMap. (Possible to unify with previously mentioned animation effect)

Render Surface ownership passing should happen at pending tree to active tree push on compositor thread.

Scrolling offset is shared between pending and active tree, and scrolling offset sync needs to happen between main thread and compositor thread.

Animation sync may need to happen both over main/compositor thread boundary as well as between active and pending tree.