place sidebar: Make removing bookmarks work again
place sidebar: Make removing bookmarks work again

This was accidentally broken in ae8c07c67cfa83d967 when I
forgot to switch the sense of a condition.

davidgumberg/gtk,jadahl/gtk,alexlarsson/gtk,Adamovskiy/gtk,jigpu/gtk,davidgumberg/gtk,Adamovskiy/gtk,davidgumberg/gtk,jadahl/gtk,jigpu/gtk,jigpu/gtk,grubersjoe/adwaita,jadahl/gtk,alexlarsson/gtk,Adamovskiy/gtk,jadahl/gtk,chergert/gtk,chergert/gtk,davidgumberg/gtk,jigpu/gtk,jigpu/gtk,grubersjoe/adwaita,grubersjoe/adwaita,grubersjoe/adwaita,Adamovskiy/gtk,chergert/gtk,chergert/gtk,jigpu/gtk,grubersjoe/adwaita,jadahl/gtk,Adamovskiy/gtk,alexlarsson/gtk,davidgumberg/gtk,chergert/gtk,Adamovskiy/gtk,alexlarsson/gtk,Adamovskiy/gtk,alexlarsson/gtk,davidgumberg/gtk,jigpu/gtk,jadahl/gtk,jadahl/gtk,grubersjoe/adwaita,jadahl/gtk,Adamovskiy/gtk,chergert/gtk,davidgumberg/gtk,grubersjoe/adwaita,chergert/gtk,chergert/gtk,alexlarsson/gtk,alexlarsson/gtk,alexlarsson/gtk,jigpu/gtk,grubersjoe/adwaita,davidgumberg/gtk