Call done() in websockets/opening-handshake/003-sets-origin.worker.js (web-platform-tests#11527)

This prevents the test harness to time out.

Author: zcorpan

websockets/opening-handshake/003-sets-origin.worker.js

@@ -15,3 +15,4 @@ async_test(function(t) {
   })
   ws.onerror = ws.onclose = t.unreached_func();
 }, "W3C WebSocket API - origin set in a Worker");
+done();