[gtk] (3 commits) Non-fast-forward update to branch heif-demo

[Matthias Clasen <matthiasc src gnome org>]

The branch 'heif-demo' 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:

  d1e4770... Add a quick-and-dirty heif loading test
  23c9e92... widget-factory: Add an hdr image example
  9a2e59b... wip: Expose more GdkColorProfile api
  62581f2... testheif: Interpret some nclx profiles
  a118e96... Add gdk_color_profile_new_from_cicp
  436d2f3... testheif: Use gdk_color_profile_new_for_cicp

Commits added to the branch:

  e51dc6b... Add gdk_color_profile_new_from_cicp
  b4d535f... Add a quick-and-dirty heif loading test
  d84a297... widget-factory: Add an hdr image example