stackswitcher: Don't do unneeded update
stackswitcher: Don't do unneeded update

The update of the needs-attention state is done via its own property,
so it doesn't need to be done via visibility changes.

This patch is largely the result of inspecting the code due to a warning
and not a result of testing. So if issues pop up that bisect back to
this patch, that's why.

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