anchor.diff:  
   import 'package:grinder/grinder.dart';
   import 'package:intl/intl.dart';
  -import 'package:polymer/builder.dart' as polymer;
   
   final NumberFormat _NF = new NumberFormat.decimalPattern();
   
  
positive.code:   runCommandSync(context, 'rm -rf build/chrome-app/spark/spark_test.dart');
  
    // zip spark.zip . -r -q -x .*
    Directory.current = 'build/chrome-app/spark';
    runCommandSync(context, 'zip ../../../dist/spark.zip . -qr -x .*');
    Directory.current = '../../..';
    printSize(context, new File('dist/spark.zip'));
  }
  
  
negative.code:   startGrinder();
  }
  
  void runCommandSync(GrinderContext context, String command, {String cwd}) {
    context.log(command);
  
    var result = Process.runSync(
        '/bin/sh', ['-c', command], workingDirectory: cwd);
  
    if (result.stdout.isNotEmpty) {
      context.log(result.stdout);
    }
    if (result.stderr.isNotEmpty) {
      context.log(result.stderr);
    }
  
    if (result.exitCode > 0) {
      context.fail("exit code ${result.exitCode}");
    }
  }
  
  String getCommandOutput(String command) {
  