anchor.diff:  import '../base/file_system.dart';
   import '../base/logger.dart';
   import '../base/process.dart';
  -import '../base/process_manager.dart';
   import '../base/utils.dart';
   import '../build_info.dart';
   import '../compile.dart';
  
positive.code:     printError('Missing input files: $missingInputs');
      return null;
    }
    if (!processManager.canRun(genSnapshot)) {
      printError('Cannot locate the genSnapshot executable');
      return null;
    }
  
    final List<String> genSnapshotCmd = <String>[];
    // iOS gen_snapshot is a multi-arch binary. Running as an i386 binary will
    // generate armv7 code. Running as an x86_64 binary will generate arm64
    // code. /usr/bin/arch can be used to run binaries with the specified
    // architecture.
    //
    // TODO(cbracken): update the GenSnapshot class to handle AOT builds.
    if (platform == TargetPlatform.ios)
      genSnapshotCmd.addAll(<String>['arch', '-x86_64']);
    genSnapshotCmd.addAll(<String>[
      genSnapshot,
      '--await_is_keyword',
      '--vm_snapshot_data=$vmSnapshotData',
      '--isolate_snapshot_data=$isolateSnapshotData',
      '--packages=${packageMap.packagesPath}',
      '--url_mapping=dart:ui,$uiPath',
      '--url_mapping=dart:vmservice_io,$vmServicePath',
      '--print_snapshot_sizes',
      '--dependencies=$dependencies',
      '--causal_async_stacks',
    ]);
  
    if ((extraFrontEndOptions != null) && extraFrontEndOptions.isNotEmpty)
      printTrace('Extra front-end options: $extraFrontEndOptions');
  
    if ((extraGenSnapshotOptions != null) && extraGenSnapshotOptions.isNotEmpty) {
      printTrace('Extra gen-snapshot options: $extraGenSnapshotOptions');
      genSnapshotCmd.addAll(extraGenSnapshotOptions);
    }
  
    if (!interpreter) {
      genSnapshotCmd.add('--embedder_entry_points_manifest=$vmEntryPoints');
      genSnapshotCmd.add('--embedder_entry_points_manifest=$ioEntryPoints');
    }
  
    // iOS symbols used to load snapshot data in the engine.
  
negative.code:   }
  
    if (buildMode != BuildMode.release) {
      genSnapshotArgs.addAll(<String>[
        '--no-checked',
        '--conditional_directives',
      ]);
  