[gtk+] (6 commits) Non-fast-forward update to branch wip/cosimoc/combobox-gadget

[Cosimo Cecchi <cosimoc src gnome org>]

The branch 'wip/cosimoc/combobox-gadget' 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:

  2c5e7ec... combobox: use GtkIcon to render button arrow
  b2f36a2... combobox: remove unneeded check
  231ac90... combobox: trivial code cleanup

Commits added to the branch:

  8c18674... combobox: use GtkIcon to render button arrow
  6b03ba5... combobox: remove unneeded check
  31b041b... combobox: trivial code cleanup
  3d82548... combobox: use a private variable when possible
  734d2e8... combobox: port to use a gadget
  6588690... combobox: deprecate shadow-type style property