[librsvg] filters: remove unused pub method

[Paolo Borelli <pborelli src gnome org>]

commit fdc2e0a5a8f159dbb49f30543140a70805e9e1d5
Author: Paolo Borelli <pborelli gnome org>
Date:   Wed Jan 1 23:16:54 2020 +0100

    filters: remove unused pub method

 rsvg_internals/src/filters/context.rs | 10 ++--------
 1 file changed, 2 insertions(+), 8 deletions(-)
---
diff --git a/rsvg_internals/src/filters/context.rs b/rsvg_internals/src/filters/context.rs
index f3a0324a..0fb27319 100644
--- a/rsvg_internals/src/filters/context.rs
+++ b/rsvg_internals/src/filters/context.rs
@@ -172,12 +172,6 @@ impl FilterContext {
         &self.computed_from_node_being_filtered
     }
 
-    /// Returns the surface corresponding to the last filter primitive's result.
-    #[inline]
-    pub fn last_result(&self) -> Option<&FilterOutput> {
-        self.last_result.as_ref()
-    }
-
     /// Returns the surface corresponding to the source graphic.
     #[inline]
     pub fn source_graphic(&self) -> &SharedImageSurface {
@@ -338,8 +332,8 @@ impl FilterContext {
             // No value => use the last result.
             // As per the SVG spec, if the filter primitive is the first in the chain, return the
             // source graphic.
-            if let Some(output) = self.last_result().cloned() {
-                return Ok(FilterInput::PrimitiveOutput(output));
+            if let Some(output) = self.last_result.as_ref() {
+                return Ok(FilterInput::PrimitiveOutput(output.clone()));
             } else {
                 return Ok(FilterInput::StandardInput(self.source_graphic().clone()));
             }