If an attribute is defined without value, the generated text should be 'a=key' rather than 'a=key:'. For media-level, it has already been done. https://bugzilla.gnome.org/show_bug.cgi?id=789742
If an attribute is defined without value, the generated text should be 'a=key' rather than 'a=key:'. For media-level, it has already been done. https://bugzilla.gnome.org/show_bug.cgi?id=789742