Remove frame around media action icons
Summary:
We were inconsistent on that and it can get in way with placement on buttons.
Also Research showed that many established media players do not per se feature
a frame around their media control buttons.
Reviewers: Breeze, VDG, andreask, ngraham
Reviewed By: VDG, andreask, ngraham
Subscribers: ngraham, mart, Frameworks
Tags: Frameworks
Differential Revision: https://phabricator.kde.org/D11049