wm: Don't subtract the margins from the configured size

When we moved the configure event size to being based on the window
geometry, we changed the coordinates of the configure request to being
frame geometry based. Frame geometry includes titlebar and border, but
not shadow margins.

Tested-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>

xwayland/window-manager.c

@@ -2188,15 +2188,12 @@ send_configure(struct weston_surface *surface, int32_t width, int32_t height)
 	struct theme *t = window->wm->theme;
 	int vborder, hborder;
 
-	if (window->fullscreen) {
+	if (window->decorate) {
+		hborder = 2 * t->width;
+		vborder = t->titlebar_height + t->width;
+	} else {
 		hborder = 0;
 		vborder = 0;
-	} else if (window->decorate) {
-		hborder = 2 * (t->margin + t->width);
-		vborder = 2 * t->margin + t->titlebar_height + t->width;
-	} else {
-		hborder = 2 * t->margin;
-		vborder = 2 * t->margin;
 	}
 
 	if (width > hborder)