D10236: [libinput] Ensure Event::device returns a proper Device

[Aleksandar Varagic]

Restricted Application edited projects, added KWin; removed Plasma.

REPOSITORY
  R108 KWin

REVISION DETAIL
  https://phabricator.kde.org/D10236

To: graesslin, #kwin, #plasma, fvogt
Cc: plasma-devel, kwin, iodelay, bwowk, ZrenBot, progwolff, lesliezhai, 
ali-mohamed, hardening, jensreuterberg, abetts, sebas, apol, mart