[librsvg] shared_surface: remove unused method

[Paolo Borelli <pborelli src gnome org>]

commit f9a4fb185e2e799351c2afe166d5d30850301e6e
Author: Paolo Borelli <pborelli gnome org>
Date:   Mon Jan 13 01:31:01 2020 +0100

    shared_surface: remove unused method

 rsvg_internals/src/surface_utils/shared_surface.rs | 12 ------------
 1 file changed, 12 deletions(-)
---
diff --git a/rsvg_internals/src/surface_utils/shared_surface.rs 
b/rsvg_internals/src/surface_utils/shared_surface.rs
index 58fe40a0..f8a3bc2b 100644
--- a/rsvg_internals/src/surface_utils/shared_surface.rs
+++ b/rsvg_internals/src/surface_utils/shared_surface.rs
@@ -4,7 +4,6 @@ use std::marker::PhantomData;
 use std::ptr::NonNull;
 
 use gdk_pixbuf::{Colorspace, Pixbuf};
-use glib::translate::{Stash, ToGlibPtr};
 use nalgebra::{storage::Storage, Dim, Matrix};
 
 use crate::rect::{IRect, Rect};
@@ -1139,17 +1138,6 @@ impl SharedImageSurface {
             self.surface_type.combine(other.surface_type),
         )
     }
-
-    /// Returns a raw pointer to the underlying surface.
-    ///
-    /// # Safety
-    /// The returned pointer must not be used to modify the surface.
-    #[inline]
-    pub unsafe fn to_glib_none(
-        &self,
-    ) -> Stash<'_, *mut cairo_sys::cairo_surface_t, cairo::ImageSurface> {
-        self.surface.to_glib_none()
-    }
 }
 
 /// Performs the arithmetic composite operation. Public for benchmarking.