[gtk/wip/chergert/quartz4u] add getter for surface backpointer

[Christian Hergert <chergert src gnome org>]

commit 6df0dbf2b447a9524cce854e7af0a952c6f25152
Author: Christian Hergert <chergert redhat com>
Date:   Thu Apr 30 13:57:32 2020 -0700

    add getter for surface backpointer

 gdk/macos/GdkMacosWindow.c | 5 +++++
 gdk/macos/GdkMacosWindow.h | 1 +
 2 files changed, 6 insertions(+)
---
diff --git a/gdk/macos/GdkMacosWindow.c b/gdk/macos/GdkMacosWindow.c
index 70b781c0b0..b62a706bed 100644
--- a/gdk/macos/GdkMacosWindow.c
+++ b/gdk/macos/GdkMacosWindow.c
@@ -657,4 +657,9 @@
   [self setStyleMask:style_mask];
 }
 
+-(GdkMacosSurface *)getGdkSurface
+{
+  return self->gdkSurface;
+}
+
 @end
diff --git a/gdk/macos/GdkMacosWindow.h b/gdk/macos/GdkMacosWindow.h
index 1c7277a1ff..3f1c6f337d 100644
--- a/gdk/macos/GdkMacosWindow.h
+++ b/gdk/macos/GdkMacosWindow.h
@@ -53,6 +53,7 @@
 -(void)hide;
 -(BOOL)isInManualResizeOrMove;
 -(BOOL)isInMove;
+-(GdkMacosSurface *)getGdkSurface;
 -(void)setGdkSurface:(GdkMacosSurface *)surface;
 -(void)setStyleMask:(NSWindowStyleMask)styleMask;
 -(void)showAndMakeKey:(BOOL)makeKey;