Fix breeze dialog background with Qt 5.12.2
style elements without type="text/css" were ignored before, but now they act as
if type was set. Set id and style properly to restore the working behaviour.
Installed new files on a system with Qt 5.12.2, wiped the SVG cache
and it looks fine again.
Reviewers: Plasma, rooty
Reviewed By: rooty
Subscribers: acooligan, filipf, heikobecker, falqueto, rooty, Zren, arojas, rikmills, asturmlechner, kde-frameworks-devel, plasma-devel
Differential Revision: https://phabricator.kde.org/D19821