[gtk] (3 commits) Non-fast-forward update to branch test-text-buffer-undo

[Matthias Clasen <matthiasc src gnome org>]

The branch 'test-text-buffer-undo' 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:

  b817047... Add tests for text buffer history
  f921ad1... textbuffer: Improve the docs
  dcc3820... textbuffer: Add some docs for undo

Commits added to the branch:

  0268c9d... Add tests for text buffer history
  994a38c... textbuffer: Improve the docs
  ffbfafb... textbuffer: Add some docs for undo