view: use saved geometry for borders if needed

This fixes the issues caused by 60f06a1 and greatly simplifies the code.
Turns out we were already tracking the dimensions needed.

river/XwaylandView.zig

@@ -114,15 +114,6 @@ pub fn getTitle(self: Self) [*:0]const u8 {
     return self.wlr_xwayland_surface.title;
 }
 
-pub fn getActualBox(self: Self) Box {
-    return .{
-        .x = self.wlr_xwayland_surface.x,
-        .y = self.wlr_xwayland_surface.y,
-        .width = self.wlr_xwayland_surface.width,
-        .height = self.wlr_xwayland_surface.height,
-    };
-}
-
 /// Called when the xwayland surface is destroyed
 fn handleDestroy(listener: ?*c.wl_listener, data: ?*c_void) callconv(.C) void {
     const self = @fieldParentPtr(Self, "listen_destroy", listener.?);