Remove a redundant check
Remove a redundant check

gtk_widget_show/_hide already check the widget's visibility.

https://bugzilla.gnome.org/show_bug.cgi?id=728135

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