anchor.diff:     */
     static const String INCREMENTAL_RESOLUTION_VALIDATION =
         "incremental-resolution-validation";
  +
  +  /**
  +   * The name of the option used to cause instrumentation to also be written to
  +   * a local file.
  +   */
  +  static const String INSTRUMENTATION_LOG_FILE = "instrumentation-log-file";
   
     /**
      * The name of the option used to enable instrumentation.
  
positive.code:         help: "enable validation of incremental resolution results (slow)",
          defaultsTo: false,
          negatable: false);
      parser.addFlag(
          INTERNAL_PRINT_TO_CONSOLE,
          help: "enable sending `print` output to the console",
  
negative.code:       defaultSdk = DirectoryBasedDartSdk.defaultSdk;
      }
  
      if (instrumentationServer != null) {
        String filePath = results[INSTRUMENTATION_LOG_FILE];
        if (filePath != null) {
          instrumentationServer = new MulticastInstrumentationServer(
              [instrumentationServer, new FileInstrumentationServer(filePath)]);
        }
      }
      InstrumentationService service =
          new InstrumentationService(instrumentationServer);
      service.logVersion(
  