[gtk/wip/chergert/macos-iosurface] dont use setOpaque override anymore

[Christian Hergert <chergert src gnome org>]

commit b578c6504cfb43e3b5f83b106fc25bdd253b80b4
Author: Christian Hergert <christian hergert me>
Date:   Fri Feb 11 16:26:10 2022 -0800

    dont use setOpaque override anymore
    
    we can use setContentsOpaque instead

 gdk/macos/GdkMacosTile.c | 10 ----------
 1 file changed, 10 deletions(-)
---
diff --git a/gdk/macos/GdkMacosTile.c b/gdk/macos/GdkMacosTile.c
index 48f38e1e6d..ef0f7bfb5b 100644
--- a/gdk/macos/GdkMacosTile.c
+++ b/gdk/macos/GdkMacosTile.c
@@ -35,16 +35,6 @@
   return self;
 }
 
--(void)setOpaque:(BOOL)opaque
-{
-  [super setOpaque:opaque];
-
-  if (opaque)
-    self.backgroundColor = NSColor.blackColor.CGColor;
-  else
-    self.backgroundColor = NSColor.clearColor.CGColor;
-}
-
 -(void)swapBuffer:(IOSurfaceRef)buffer withRect:(CGRect)rect
 {
   self.contents = nil;