xdg-shell-v6: don't destroy role resources on unmap

The motivation for this is:
- `get_popup` and `get_toplevel` allocate role-specific resources.
- On the first non-null commit, the surface gets mapped.
- On a null commit, the surface gets unmapped. It can be mapped
  again with a non-null commit.
- When the role object (xdg-toplevel or xdg-popup) is
  destroyed, the surface is unmapped and role-specific resources
  are destroyed. The client can call `get_popup` or `get_toplevel`
  again on that surface.
- When the xdg-surface object is destroyed, the surface is
  unmapped, role-specific resources are destroyed and the surface
  itself is destroyed.

0 files changed, 0 insertions, 0 deletions