diff -p -up comm-beta/mozilla/gfx/thebes/gfxPlatform.cpp.system-cairo comm-beta/mozilla/gfx/thebes/gfxPlatform.cpp
--- comm-beta/mozilla/gfx/thebes/gfxPlatform.cpp.system-cairo	2012-12-23 20:02:44.050749957 +0100
+++ comm-beta/mozilla/gfx/thebes/gfxPlatform.cpp	2012-12-23 20:55:29.659994903 +0100
@@ -507,11 +507,9 @@ void SourceBufferDestroy(void *srcSurfUD
   delete static_cast<SourceSurfaceUserData*>(srcSurfUD);
 }
 
-void SourceSnapshotDetached(cairo_surface_t *nullSurf)
+void SourceSnapshotDetached(void *nullSurf)
 {
-  gfxImageSurface* origSurf =
-    static_cast<gfxImageSurface*>(cairo_surface_get_user_data(nullSurf, &kSourceSurface));
-
+  gfxImageSurface *origSurf = static_cast<gfxImageSurface*>(nullSurf);
   origSurf->SetData(&kSourceSurface, NULL, NULL);
 }
 
@@ -626,14 +624,8 @@ gfxPlatform::GetSourceSurfaceForSurface(
 
     }
 
-    cairo_surface_t *nullSurf =
-	cairo_null_surface_create(CAIRO_CONTENT_COLOR_ALPHA);
-    cairo_surface_set_user_data(nullSurf,
-                                &kSourceSurface,
-                                imgSurface,
-                                NULL);
-    cairo_surface_attach_snapshot(imgSurface->CairoSurface(), nullSurf, SourceSnapshotDetached);
-    cairo_surface_destroy(nullSurf);
+    cairo_surface_set_mime_data(imgSurface->CairoSurface(), "mozilla/magic",
+		(const unsigned char *) "data", 4, SourceSnapshotDetached, imgSurface.get());
   }
 
   SourceSurfaceUserData *srcSurfUD = new SourceSurfaceUserData;