tests textiter: unit tests for visible word boundaries
tests textiter: unit tests for visible word boundaries

As the FIXME comments show, there are several problems.

https://bugzilla.gnome.org/show_bug.cgi?id=618852

Lyude/gtk-,ahodesuka/gtk,alexlarsson/gtk,grubersjoe/adwaita,ahodesuka/gtk,grubersjoe/adwaita,Lyude/gtk-,jigpu/gtk,jessevdk/gtk,Adamovskiy/gtk,grubersjoe/adwaita,davidgumberg/gtk,ahodesuka/gtk,jigpu/gtk,davidgumberg/gtk,Adamovskiy/gtk,alexlarsson/gtk,grubersjoe/adwaita,jigpu/gtk,davidgumberg/gtk,chergert/gtk,jadahl/gtk,jadahl/gtk,jigpu/gtk,Lyude/gtk-,jigpu/gtk,jessevdk/gtk,grubersjoe/adwaita,jigpu/gtk,davidgumberg/gtk,alexlarsson/gtk,jessevdk/gtk,jessevdk/gtk,chergert/gtk,jadahl/gtk,chergert/gtk,Lyude/gtk-,jessevdk/gtk,alexlarsson/gtk,Lyude/gtk-,Lyude/gtk-,Adamovskiy/gtk,chergert/gtk,jadahl/gtk,jadahl/gtk,Adamovskiy/gtk,jadahl/gtk,chergert/gtk,jessevdk/gtk,jadahl/gtk,Adamovskiy/gtk,davidgumberg/gtk,alexlarsson/gtk,grubersjoe/adwaita,davidgumberg/gtk,Lyude/gtk-,ahodesuka/gtk,davidgumberg/gtk,ahodesuka/gtk,chergert/gtk,Adamovskiy/gtk,ahodesuka/gtk,chergert/gtk,alexlarsson/gtk,jessevdk/gtk,Adamovskiy/gtk,grubersjoe/adwaita,ahodesuka/gtk,jadahl/gtk,jigpu/gtk,jigpu/gtk,chergert/gtk,Adamovskiy/gtk,grubersjoe/adwaita,ahodesuka/gtk,alexlarsson/gtk,Lyude/gtk-,alexlarsson/gtk,davidgumberg/gtk