fix: ensure TracingAgent in place for SWs (#31475)

Co-authored-by: Shelley Vohr <[email protected]>

shell/renderer/web_worker_observer.cc

@@ -50,6 +50,10 @@ void WebWorkerObserver::WorkerScriptReadyForEvaluation(
   // Start the embed thread.
   node_bindings_->PrepareMessageLoop();
 
+  // Setup node tracing controller.
+  if (!node::tracing::TraceEventHelper::GetAgent())
+    node::tracing::TraceEventHelper::SetAgent(node::CreateAgent());
+
   // Setup node environment for each window.
   bool initialized = node::InitializeContext(worker_context);
   CHECK(initialized);