aeb19f2f4d
Setting up the sync_to_vblank in the MasterClock is a bit too late as the MasterClock can be created after a StageWindow has been created and realized (and therefore all of its Cogl/GL state setup already). So move the setup to the backend, prior to any StageWindow creation. https://bugzilla.gnome.org/show_bug.cgi?id=754938