[librsvg] FilterContext::into_output(): propagate errors more simply

[Federico Mena Quintero <federico src gnome org>]

commit f2b79f577c162bb30e1dec5b6c9bf33cf7e81175
Author: Federico Mena Quintero <federico gnome org>
Date:   Sun Sep 23 19:01:40 2018 -0500

    FilterContext::into_output(): propagate errors more simply

 rsvg_internals/src/filters/context.rs | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)
---
diff --git a/rsvg_internals/src/filters/context.rs b/rsvg_internals/src/filters/context.rs
index b75a4a1e..100e0786 100644
--- a/rsvg_internals/src/filters/context.rs
+++ b/rsvg_internals/src/filters/context.rs
@@ -390,10 +390,9 @@ impl FilterContext {
                     cairo::Format::ARgb32,
                     self.source_surface.width(),
                     self.source_surface.height(),
-                ).map_err(FilterError::CairoError)?;
+                )?;
 
-                SharedImageSurface::new(empty_surface, SurfaceType::AlphaOnly)
-                    .map_err(FilterError::CairoError)
+                Ok(SharedImageSurface::new(empty_surface, SurfaceType::AlphaOnly)?)
             }
         }
     }