notebook: make sure the allocation keeps track of the tab curvature
notebook: make sure the allocation keeps track of the tab curvature

This was a genuine typo, because "padding" was calculated but unused in
this branch of the code.

davidgumberg/gtk,ahodesuka/gtk,davidt/gtk,msteinert/gtk,Distrotech/gtk2,davidt/gtk,grubersjoe/adwaita,Distrotech/gtk2,davidgumberg/gtk,jadahl/gtk,Lyude/gtk-,simokivimaki/gtk,alexlarsson/gtk,grubersjoe/adwaita,Adamovskiy/gtk,simokivimaki/gtk,jessevdk/gtk,jigpu/gtk,ahodesuka/gtk,jessevdk/gtk,Adamovskiy/gtk,Distrotech/gtk2,jigpu/gtk,jadahl/gtk,alexlarsson/gtk,Lyude/gtk-,davidt/gtk,Lyude/gtk-,ahodesuka/gtk,Sidnioulz/SandboxGtk,davidt/gtk,Distrotech/gtk2,jigpu/gtk,chergert/gtk,chergert/gtk,jadahl/gtk,bratsche/gtk-,grubersjoe/adwaita,jigpu/gtk,Lyude/gtk-,Adamovskiy/gtk,bratsche/gtk-,grubersjoe/adwaita,msteinert/gtk,alexlarsson/gtk,bratsche/gtk-,jessevdk/gtk,jigpu/gtk,chergert/gtk,davidgumberg/gtk,jessevdk/gtk,bratsche/gtk-,ahodesuka/gtk,chergert/gtk,Sidnioulz/SandboxGtk,Lyude/gtk-,Adamovskiy/gtk,Lyude/gtk-,ebassi/gtk,simokivimaki/gtk,ebassi/gtk,grubersjoe/adwaita,simokivimaki/gtk,jadahl/gtk,davidgumberg/gtk,bratsche/gtk-,simokivimaki/gtk,simokivimaki/gtk,davidt/gtk,alexlarsson/gtk,jigpu/gtk,bratsche/gtk-,grubersjoe/adwaita,msteinert/gtk,Lyude/gtk-,grubersjoe/adwaita,msteinert/gtk,ebassi/gtk,jadahl/gtk,ahodesuka/gtk,alexlarsson/gtk,grubersjoe/adwaita,chergert/gtk,Distrotech/gtk2,jadahl/gtk,davidt/gtk,Adamovskiy/gtk,Sidnioulz/SandboxGtk,davidgumberg/gtk,ahodesuka/gtk,jigpu/gtk,Sidnioulz/SandboxGtk,jadahl/gtk,Lyude/gtk-,jigpu/gtk,chergert/gtk,jessevdk/gtk,davidgumberg/gtk,Sidnioulz/SandboxGtk,ebassi/gtk,jessevdk/gtk,alexlarsson/gtk,ebassi/gtk,davidgumberg/gtk,ahodesuka/gtk,msteinert/gtk,ebassi/gtk,Sidnioulz/SandboxGtk,jadahl/gtk,Adamovskiy/gtk,chergert/gtk,davidgumberg/gtk,jessevdk/gtk,alexlarsson/gtk,Adamovskiy/gtk,alexlarsson/gtk,msteinert/gtk,chergert/gtk,ahodesuka/gtk,Adamovskiy/gtk,Distrotech/gtk2