anchor.diff:  ArgParser argParser = new ArgParser()
     ..addOption('target',
         help: 'target platform', defaultsTo: 'vm', allowed: ['vm', 'flutter'])
  +  ..addOption('cache',
  +      help: 'caching policy used by the compiler',
  +      defaultsTo: 'protected',
  +      allowed: ['evicting', 'memory', 'protected'])
     ..addOption('sdk-summary', help: 'Location of the sdk outline.dill file')
     ..addOption('sdk-library-specification',
         help: 'Location of the '
  
positive.code:   }
  
    var dir = Directory.systemTemp.createTempSync('ikg-cache');
    compilerOptions.byteStore = new ProtectedFileByteStore(dir.path);
  
    var timer1 = new Stopwatch()..start();
    var generator =
  
negative.code: import 'dart:io' hide FileSystemEntity;
  
  import 'package:args/args.dart';
  import 'package:front_end/byte_store.dart';
  import 'package:front_end/file_system.dart' show FileSystemEntity;
  import 'package:front_end/front_end.dart';
  import 'package:front_end/incremental_kernel_generator.dart';
  import 'package:front_end/memory_file_system.dart';
  import 'package:front_end/physical_file_system.dart';
  import 'package:front_end/src/byte_store/protected_file_byte_store.dart';
  import 'package:kernel/target/flutter.dart';
  import 'package:kernel/target/targets.dart';
  
  