[gtk] (3 commits) Non-fast-forward update to branch wip/baedert/single-node-window

[Timm Bäder <baedert src gnome org>]

The branch 'wip/baedert/single-node-window' 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:

  952329b... Adwaita: style updates for new window node hierarchy
  7687d49... update documentation for new style classes and node names

Commits added to the branch:

  7fc4b54... Adwaita: style updates for new window node hierarchy
  5b0410e... update documentation for new style classes and node names
  de32c56... window: Create default titlebar directly in realize