Replace uses of for foo in bar.iter(),

and `for foo in bar.iter_mut(), and for foo in bar.into_iter()
(continuation of #7197)

components/devtools/lib.rs

@@ -297,7 +297,7 @@ fn run_server(sender: Sender<DevtoolsControlMsg>,
                 columnNumber: console_message.columnNumber,
             },
         };
-        for stream in console_actor.streams.borrow_mut().iter_mut() {
+        for mut stream in &mut *console_actor.streams.borrow_mut() {
             stream.write_json_packet(&msg);
         }
     }