GtkSearchBar: Don't vexpand
GtkSearchBar: Don't vexpand

It turns out that setting vexpand to its default value has
side-effects that we need.

https://bugzilla.gnome.org/show_bug.cgi?id=751447

chergert/gtk,Adamovskiy/gtk,grubersjoe/adwaita,grubersjoe/adwaita,chergert/gtk,alexlarsson/gtk,chergert/gtk,davidgumberg/gtk,jadahl/gtk,Adamovskiy/gtk,jadahl/gtk,jadahl/gtk,davidgumberg/gtk,grubersjoe/adwaita,davidgumberg/gtk,grubersjoe/adwaita,chergert/gtk,jadahl/gtk,Adamovskiy/gtk,jigpu/gtk,Adamovskiy/gtk,chergert/gtk,Adamovskiy/gtk,grubersjoe/adwaita,jadahl/gtk,jigpu/gtk,chergert/gtk,chergert/gtk,davidgumberg/gtk,grubersjoe/adwaita,jadahl/gtk,grubersjoe/adwaita,alexlarsson/gtk,alexlarsson/gtk,alexlarsson/gtk,jadahl/gtk,davidgumberg/gtk,jigpu/gtk,jigpu/gtk,jigpu/gtk,jigpu/gtk,alexlarsson/gtk,davidgumberg/gtk,davidgumberg/gtk,davidgumberg/gtk,Adamovskiy/gtk,jadahl/gtk,alexlarsson/gtk,grubersjoe/adwaita,jigpu/gtk,chergert/gtk,Adamovskiy/gtk,jigpu/gtk,alexlarsson/gtk,alexlarsson/gtk,Adamovskiy/gtk