anchor.diff:      }
       // A worker has no script tag - so get an url from a stack-trace.
       if (_globalState.isWorker) return computeThisScriptFromTrace();
  +    // An isolate that doesn't support workers, but doesn't have a
  +    // currentScript either. This is most likely a Chrome extension.
       return null;
     }
   
  
positive.code:   /** The entry point given by [startRootIsolate]. */
    final Function entry;
  
    _Manager(this.entry) {
      _nativeDetectEnvironment();
      topEventLoop = new _EventLoop();
      isolates = new Map<int, _IsolateContext>();
  
negative.code:     throw new ArgumentError("Arguments to main must be a List: $args");
    }
    _globalState = new _Manager(entry);
    _globalState._initialize();
  
    // Don't start the main loop again, if we are in a worker.
    if (_globalState.isWorker) return;
  