Fix gdk_window_get_geometry for native children with non-native parent
Fix gdk_window_get_geometry for native children with non-native parent

gdk_window_get_geometry calls the native function for all non-native
windows. This returns coords relative to the native parent. We need
to convert this to be relative to the client side parent.

This fixes DnD coordinates in firefox (bug 588437).

grubersjoe/adwaita,Adamovskiy/gtk,ahodesuka/gtk,chipx86/gtk,zsx/gtk,Adamovskiy/gtk,alexlarsson/gtk,Lyude/gtk-,Adamovskiy/gtk,davidgumberg/gtk,jadahl/gtk,alexlarsson/gtk,Distrotech/gtk,Sidnioulz/SandboxGtk,davidt/gtk,johne53/MB3Gtk-2,jessevdk/gtk,zsx/gtk,chergert/gtk,Distrotech/gtk,chergert/gtk,jessevdk/gtk,alexlarsson/gtk,jigpu/gtk,Distrotech/gtk,jessevdk/gtk,Distrotech/gtk2,msteinert/gtk,zsx/gtk,Sidnioulz/SandboxGtk,Unity-Technologies/gtk,Distrotech/gtk2,Lyude/gtk-,msteinert/gtk,zsx/gtk,davidgumberg/gtk,bratsche/gtk-,davidgumberg/gtk,simokivimaki/gtk,davidgumberg/gtk,grubersjoe/adwaita,grubersjoe/adwaita,msteinert/gtk,Adamovskiy/gtk,jigpu/gtk,davidgumberg/gtk,Distrotech/gtk2,Distrotech/gtk,Distrotech/gtk2,johne53/MB3Gtk-2,jessevdk/gtk,jadahl/gtk,chergert/gtk,jadahl/gtk,ahodesuka/gtk,Unity-Technologies/gtk,ebassi/gtk,bratsche/gtk-,davidgumberg/gtk,jadahl/gtk,davidt/gtk,jigpu/gtk,msteinert/gtk,simokivimaki/gtk,grubersjoe/adwaita,johne53/MB3Gtk-2,Distrotech/gtk,Lyude/gtk-,nacho/gtk-,grubersjoe/adwaita,grubersjoe/adwaita,alexlarsson/gtk,Distrotech/gtk2,jessevdk/gtk,simokivimaki/gtk,chipx86/gtk,davidt/gtk,chipx86/gtk,Lyude/gtk-,jadahl/gtk,Lyude/gtk-,Lyude/gtk-,alexlarsson/gtk,jadahl/gtk,chipx86/gtk,ebassi/gtk,msteinert/gtk,davidgumberg/gtk,Adamovskiy/gtk,jadahl/gtk,bratsche/gtk-,simokivimaki/gtk,Sidnioulz/SandboxGtk,ahodesuka/gtk,Distrotech/gtk2,jessevdk/gtk,Sidnioulz/SandboxGtk,Lyude/gtk-,Unity-Technologies/gtk,simokivimaki/gtk,chergert/gtk,alexlarsson/gtk,bratsche/gtk-,Sidnioulz/SandboxGtk,chergert/gtk,jadahl/gtk,nacho/gtk-,davidt/gtk,grubersjoe/adwaita,zsx/gtk,Lyude/gtk-,jigpu/gtk,bratsche/gtk-,chergert/gtk,grubersjoe/adwaita,nacho/gtk-,ebassi/gtk,jigpu/gtk,msteinert/gtk,alexlarsson/gtk,jigpu/gtk,ahodesuka/gtk,ahodesuka/gtk,davidt/gtk,johne53/MB3Gtk-2,davidgumberg/gtk,ebassi/gtk,johne53/MB3Gtk-2,chergert/gtk,bratsche/gtk-,Sidnioulz/SandboxGtk,davidt/gtk,Adamovskiy/gtk,jigpu/gtk,chipx86/gtk,jessevdk/gtk,Unity-Technologies/gtk,nacho/gtk-,chergert/gtk,ebassi/gtk,ahodesuka/gtk,ahodesuka/gtk,Adamovskiy/gtk,nacho/gtk-,jigpu/gtk,ebassi/gtk,simokivimaki/gtk,alexlarsson/gtk,Adamovskiy/gtk,Unity-Technologies/gtk,ahodesuka/gtk