[gtk] (3 commits) Non-fast-forward update to branch wip/otte/for-main

[Benjamin Otte <otte src gnome org>]

The branch 'wip/otte/for-main' 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:

  a2548ed... glrenderer: Don't return NULL form render_texture()
  c5d35ac... flattenlistmodel: Fix indentation
  c837312... listview: Fix return_if_fail()s

Commits added to the branch:

  1ff66df... glrenderer: Don't return NULL form render_texture() (*)
  7c05f57... flattenlistmodel: Fix indentation (*)
  f0e7463... listview: Fix return_if_fail()s (*)

(*) This commit already existed in another branch; no separate mail sent