Server: Remove unnecessary worker fallback

The fallback will never apply, since the previous if already establishes that
workers[query._worker_key] is defined.

Author: jzaefferer

lib/server.js

@@ -36,7 +36,7 @@ exports.Server = function Server(bsClient, workers) {
     var query = url_parts.query;
 
     if (query._worker_key && workers[query._worker_key]) {
-      worker = workers[query._worker_key] || {};
+      var worker = workers[query._worker_key];
       worker.acknowledged = true;
       logger.debug("[%s] Acknowledged", getTestBrowserInfo(worker));
     }