Summary:
Won't make things go much faster since everything that was
being passed by value is refcounted but still const & is a bit faster
than refcounting
For shared pointers instead of adding const & we move them into the
destination variable saving some cpu usage but at the same time making
clear the pointer is being stored by not being const &
Reviewers: zzag
Reviewed By: zzag
Subscribers: zzag, kwin
Tags: #kwin
Differential Revision: https://phabricator.kde.org/D25022