[gtk] Non-fast-forward update to branch wip/matthiasc/sortlistmodel

[Matthias Clasen <matthiasc src gnome org>]

The branch 'wip/matthiasc/sortlistmodel' was changed in a way that was not a fast-forward update.
NOTE: This may cause problems for people pulling from the branch. For more information,
please see:

 https://wiki.gnome.org/Git/Help/NonFastForward

Commits removed from the branch:

  9b1dde6... gdk: Don't emit size-changed unless it changed

Commits added to the branch:

  cf86936... gtksor3listmodel: Track changed items precisely