servo: Merge #9813 - With WebRender, only send resize events when window size is valid (from glennw:iframe-sizing); r=pcwalton

Fixes WR 112.

Source-Repo: https://github.com/servo/servo
Source-Revision: 4035f7ae2c4925675263f514884ec702ac3d5460

servo/components/compositing/compositor.rs

@@ -353,10 +353,11 @@ impl webrender_traits::RenderNotifier for RenderNotifier {
                              pipeline_id: webrender_traits::PipelineId,
                              size: Option<Size2D<f32>>) {
         let pipeline_id = pipeline_id.from_webrender();
-        let size = size.unwrap_or(Size2D::zero());
 
-        self.constellation_chan.send(ConstellationMsg::FrameSize(pipeline_id,
-                                                                 size)).unwrap();
+        if let Some(size) = size {
+            self.constellation_chan.send(ConstellationMsg::FrameSize(pipeline_id,
+                                                                     size)).unwrap();
+        }
     }
 }