anchor.diff:        List<String> sharedOptions,
         List<String> dart2jsOptions,
         List<String> args) {
  -    List<String> arguments = <String>[];
  -    for (String argument in args) {
  +    var arguments = <String>[];
  +    for (var argument in args) {
         if (argument != "--ignore-unrecognized-flags") {
           arguments.add(argument);
         }
  
positive.code:   bool get runRuntimeDespiteMissingCompileTimeError => true;
  
    @override
    int get timeoutMultiplier => 1;
  
    @override
    bool get hasCompiler => true;
  
    @override
    List<Uri> bootstrapDependencies() => <Uri>[_plaformDill];
  
    @override
    Command createCommand(String inputFile, String outputFile,
        List<String> sharedOptions, Map<String, String> environment) {
      throw "not implemented yet";
    }
  
    @override
    CommandArtifact computeCompilationArtifact(String tempDir,
        List<String> arguments, Map<String, String> environmentOverrides) {
      Uri output =
          Uri.base.resolveUri(new Uri.directory(tempDir)).resolve("out.dill");
      String outputFileName = output.toFilePath();
      String vmPath = _vmExecutable.toFilePath();
      if (Platform.isWindows) {
        vmPath += ".exe";
      }
      List<String> compilerArguments = <String>[];
      if (!_isLegacy) {
        compilerArguments.add("--strong-mode");
      }
      compilerArguments
        ..addAll(<String>[
          "-o",
          outputFileName,
          "--platform",
          _plaformDill.toFilePath(),
        ])
        ..addAll(arguments);
  
      return new CommandArtifact(
        [
          Command.fasta(
            _compilerLocation,
            output,
            bootstrapDependencies(),
            _vmExecutable,
            compilerArguments,
            environmentOverrides,
            Repository.uri,
          )
        ],
        outputFileName,
        mimeType,
      );
    }
  
    @override
  
negative.code: }
  
  class FastaCompilerConfiguration extends CompilerConfiguration {
    static final _compilerLocation =
        Repository.uri.resolve("pkg/front_end/tool/_fasta/compile.dart");
  
    final Uri _platformDill;
  
    final Uri _vmExecutable;
  
    bool get _isLegacy => !_configuration.isStrong;
  
    factory FastaCompilerConfiguration(Configuration configuration) {
      var buildDirectory =
          Uri.base.resolveUri(new Uri.directory(configuration.buildDirectory));
  
      var dillDir = buildDirectory;
      if (configuration.useSdk) {
        dillDir = buildDirectory.resolve("dart-sdk/lib/_internal/");
      }
  
      var suffix = configuration.isStrong ? "_strong" : "";
      var platformDill = dillDir.resolve("vm_platform$suffix.dill");
  
      var vmExecutable = buildDirectory
          .resolve(configuration.useSdk ? "dart-sdk/bin/dart" : "dart");
      return new FastaCompilerConfiguration._(
          platformDill, vmExecutable, configuration);
    }
  
    FastaCompilerConfiguration._(
        this._platformDill, this._vmExecutable, Configuration configuration)
        : super._subclass(configuration);
  
    @override
    bool get useDfe => true;
  