Summary:
In order to be compatible with the monolithic Fade effect, this effect
animates special windows (e.g. notifications, etc) as well, but some
of those special windows shouldn't be animated by this effect (e.g.
KDE Plasma splash screen).
Test Plan:
Started new Plasma on Wayland session, the KDE Plasma splash screen
smoothly faded out without flickering/blinking, etc.
Reviewers: #kwin, davidedmundson
Reviewed By: #kwin, davidedmundson
Subscribers: davidedmundson, kwin
Tags: #kwin
Differential Revision: https://phabricator.kde.org/D17209
3d57324ed2