D23745: [server] Make double-buffered properties in xdg-shell double-buffered

[Vlad Zagorodniy]

zzag added a task: T11480: Make xdg-shell properties double-buffered.

REPOSITORY
  R127 KWayland

REVISION DETAIL
  https://phabricator.kde.org/D23745

To: zzag, #kwin
Cc: kde-frameworks-devel, LeGast00n, GB_2, michaelh, ngraham, bruns