anchor.diff:    // off by at max (#workers - 1).
     var p = spawnFunction(worker);
     workerPorts.add(p);
  -  p.send(new Message(Message.WORK, [sharedEnv, files]), port);
  +  p.send(new Message(Message.WORK, [sharedEnv, files]), port.toSendPort());
   
     return 0;
   }
  
positive.code:   } else {
      env.pkgRoot = absolute(normalize(args["package-root"]));
      if (!FileSystemEntity.isDirectorySync(env.pkgRoot)) {
        throw "Provided package root ${args["package-root"]} is not directory.";
      }
    }
  
    if (args["in"] == "stdin") {
      env.input = "stdin";
    } else {
      env.input = absolute(normalize(args["in"]));
      if (!FileSystemEntity.isDirectorySync(env.input) &&
          !FileSystemEntity.isFileSync(env.input)) {
        throw "Provided input ${args["in"]} is neither a directory, nor a file.";
      }
    }
  
  
negative.code:       env.sdkRoot =
          join(absolute(normalize(Platform.environment["SDK_ROOT"])), "lib");
      } else {
        fail("No SDK root found, please specify one using --sdk-root.");
      }
    } else {
      env.sdkRoot = join(absolute(normalize(args["sdk-root"])), "lib");
    }
    if (!FileSystemEntity.isDirectorySync(env.sdkRoot)) {
      fail("Provided SDK root '${args["sdk-root"]}' is not a valid SDK "
           "top-level directory");
    }
  
    if (args["package-root"] == null) {
  