D9823: Optimize: use QMetaObject::invokeMethod with functor

[David Faure]

dfaure accepted this revision.
This revision is now accepted and ready to land.

REPOSITORY
  R244 KCoreAddons

BRANCH
  master

REVISION DETAIL
  https://phabricator.kde.org/D9823

To: mwolff, dfaure, apol, mpyne
Cc: mpyne, #frameworks