GtkTextView: Preserve the cairo context around draw_layer
GtkTextView: Preserve the cairo context around draw_layer

Otherwise, draw_layer might unintentionally wreak havoc on the
regular drawing that happens between the two draw_layer calls.

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