Auto merge of #16262 - jdm:connection-pool, r=nox

Enable HTTP connection pooling

- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [X] These changes fix #15694
- [X] There are tests for these changes

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components/net/http_loader.rs

@@ -487,7 +487,9 @@ fn obtain_response(request_factory: &NetworkHttpRequestFactory,
 
         let response = match request_writer.send() {
             Ok(w) => w,
-            Err(HttpError::Io(ref io_error)) if io_error.kind() == io::ErrorKind::ConnectionAborted => {
+            Err(HttpError::Io(ref io_error))
+                if io_error.kind() == io::ErrorKind::ConnectionAborted ||
+                   io_error.kind() == io::ErrorKind::ConnectionReset => {
                 debug!("connection aborted ({:?}), possibly stale, trying new connection", io_error.description());
                 continue;
             },

components/net/resource_thread.rs

@@ -330,8 +330,7 @@ impl CoreResourceManager {
         let ua = self.user_agent.clone();
         let dc = self.devtools_chan.clone();
         let filemanager = self.filemanager.clone();
-        // FIXME(#15694): use group.connector.clone() instead.
-        let connector = create_http_connector(group.ssl_client.clone());
+        let connector = group.connector.clone();
 
         thread::Builder::new().name(format!("fetch thread for {}", init.url)).spawn(move || {
             let mut request = Request::from_init(init);