Call done() correctly in /workers/nested_worker.worker.js (#11197)

Fixes #11195.
diff --git a/workers/nested_worker.worker.js b/workers/nested_worker.worker.js
index 8848fa2..005b3c2 100644
--- a/workers/nested_worker.worker.js
+++ b/workers/nested_worker.worker.js
@@ -6,6 +6,6 @@
     worker1.onmessage = this.step_func_done(function(evt) {
         assert_equals(evt.data, "Pass");
         worker1.terminate();
-        done();
     });
 }, "Nested worker");
+done();