Keep track of the scale of the buffer set by surface.set_buffer_scale.
Calculate the height and width of the texture from the buffer depending on the
scale when it is attached.
Use buffer damage to determine the damage of the buffer when flushing damage.
Convert surface damage to buffer damage and union to the surface buffer_damage
prior to flushing damage.
Add a signal for wlr_surface destruction on the wlr_surface that compositors
can listen to to remove the surface from their state.
Implement a listener for this in the example wl_compositor to remove the
surface from its internal list of surfaces.
Destroy the surface in the compositor destroy_surface callback given when the
surface resource was created.
Add a reference to the surface resource to the wlr_surface so a compositor can
find it in its list of resources upon wlr_resource destruction.
