Auto merge of #22121 - gterzian:remove_constellation_block_in_navigation, r=paulrouget

Remove sync constellation -> embedder communication

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- [ ] `./mach build -d` does not report any errors
- [ ] `./mach test-tidy` does not report any errors
- [ ] These changes fix #22042 (github issue number if applicable).

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components/servo/lib.rs

@@ -279,6 +279,16 @@ where
                 self.compositor.on_resize_window_event();
             },
 
+            WindowEvent::AllowNavigationResponse(pipeline_id, allowed) => {
+                let msg = ConstellationMsg::AllowNavigationResponse(pipeline_id, allowed);
+                if let Err(e) = self.constellation_chan.send(msg) {
+                    warn!(
+                        "Sending allow navigation to constellation failed ({:?}).",
+                        e
+                    );
+                }
+            },
+
             WindowEvent::LoadUrl(top_level_browsing_context_id, url) => {
                 let msg = ConstellationMsg::LoadUrl(top_level_browsing_context_id, url);
                 if let Err(e) = self.constellation_chan.send(msg) {