gtk_css_value_bg_size_equal: actually compare contain values
gtk_css_value_bg_size_equal: actually compare contain values

Due to a copy-paste error, the code failed to compare the
contain members of value1 and value2.

This was found by Coverity.

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