[gtk] (5 commits) Non-fast-forward update to branch wip/baedert/for-master

[Timm Bäder <baedert src gnome org>]

The branch 'wip/baedert/for-master' 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:

  2a439ff... gsk: Make a few functions G_GNUC_PURE
  058a449... cssvalue: Make some functions pure
  e2eb2be... gl renderer: Use #ifdef for G_ENABLE_DEBUG
  8163409... cssimage: Make some function pure

Commits added to the branch:

  30bb3b5... cssvalue: Make some functions pure
  9bfabfb... cssimage: Make some function pure
  61f759d... GdkRGBA: Make snome functions pure
  724123d... gsk: Make a few functions G_GNUC_PURE
  dcfe1cc... csscolorvalue: Make some functions pure