[librsvg/wip/rust-api] CairoRenderer: add a render_element() method

[Federico Mena Quintero <federico src gnome org>]

commit e4b629afe75ea46ef76afc55668b084a97fc2a4e
Author: Federico Mena Quintero <federico gnome org>
Date:   Mon Feb 18 11:32:25 2019 -0600

    CairoRenderer: add a render_element() method

 librsvg_crate/src/lib.rs | 8 ++++++++
 1 file changed, 8 insertions(+)
---
diff --git a/librsvg_crate/src/lib.rs b/librsvg_crate/src/lib.rs
index 0d7d3ebc..39b95ace 100644
--- a/librsvg_crate/src/lib.rs
+++ b/librsvg_crate/src/lib.rs
@@ -157,4 +157,12 @@ impl<'a> CairoRenderer<'a> {
     pub fn render(&self, cr: &cairo::Context) -> Result<(), RenderingError> {
         self.handle.0.render_cairo_sub(cr, None)
     }
+
+    pub fn render_element(
+        &self,
+        cr: &cairo::Context,
+        id: Option<&str>,
+    ) -> Result<(), RenderingError> {
+        self.handle.0.render_cairo_sub(cr, id)
+    }
 }