Bug 1640567 Pass expected window position to the NativeMoveResizeWaylandPopup to avoid repositioning; r=stransky

If the position expected position of popup is not changed by the GTK (it popup fit into the screen)
we don't have to update position of nsMenuPopupFrame in Gecko view. We sent the anchor position
instead of expected popup position to the NativeMoveResizeWaylandPopup which triggered the view changes.

Differential Revision: https://phabricator.services.mozilla.com/D92043

layout/xul/nsMenuPopupFrame.cpp

@@ -1422,11 +1422,9 @@ nsresult nsMenuPopupFrame::SetPopupPosition(nsIFrame* aAnchorFrame,
           !GDK_IS_X11_DISPLAY(gdk_display_get_default())) {
         screenPoint = nsPoint(anchorRect.x, anchorRect.y);
         mAnchorRect = anchorRect;
-      } else
-#endif
-      {
-        screenPoint = AdjustPositionForAnchorAlign(anchorRect, hFlip, vFlip);
       }
+#endif
+      screenPoint = AdjustPositionForAnchorAlign(anchorRect, hFlip, vFlip);
     } else {
       // with no anchor, the popup is positioned relative to the root frame
       anchorRect = rootScreenRect;