Fix W32 theme for spinbuttons
Fix W32 theme for spinbuttons

It seems that the dec-button no longer has a "bottom" selector-thingy to
select for. Use "last-child" instead.
Use .vertical to style vertical instance differently, as last-child/first-child
meaning is inverted there.
Increase (towards 0) margins a bit, to avoid clipping the pre-light rectangle.
Use dir(rtl) selector to style horizontal instance differently for RTL locales,
where first-child is "inc".

https://bugzilla.gnome.org/show_bug.cgi?id=727022

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