Auto merge of #11556 - Manishearth:make-fetch-happen, r=jdm

Make fetch happen

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Moves XHR over to the fetch backend.

Previous PR: https://github.com/servo/servo/pull/114

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- [x] `./mach build -d` does not report any errors
- [ ] `./mach test-tidy` does not report any errors (Will fix later)

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- [x] There are tests for these changes OR
- [ ] These changes do not require tests because _____

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components/script/script_thread.rs

@@ -1962,7 +1962,7 @@ impl ScriptThread {
             script_chan: self.chan.clone(),
         };
         ROUTER.add_route(action_receiver.to_opaque(), box move |message| {
-            listener.notify(message.to().unwrap());
+            listener.notify_action(message.to().unwrap());
         });
         let response_target = AsyncResponseTarget {
             sender: action_sender,