--- a/testing/web-platform/tests/common/security-features/scope/template/worker.js.template
+++ b/testing/web-platform/tests/common/security-features/scope/template/worker.js.template
@@ -8,21 +8,16 @@ if ('DedicatedWorkerGlobalScope' in self
   onconnect = event => {
     const port = event.ports[0];
     port.onmessage = event => onMessageFromParent(event, port);
   };
 }
 
 // Receive a message from the parent and start the test.
 function onMessageFromParent(event, port) {
-  // Because this worker might receive messages from child context during
-  // tests, we first remove the listener here before staring the test
-  // (needed only for dedicated workers).
-  port.onmessage = undefined;
-
   const configurationError = "%(error)s";
   if (configurationError.length > 0) {
     port.postMessage({error: configurationError});
     return;
   }
 
   invokeRequest(event.data.subresource,
                 event.data.sourceContextList)