Remove barback from the repo.

pkg/barback/test/transformer/one_to_many.dart

-// Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
-// for details. All rights reserved. Use of this source code is governed by a
-// BSD-style license that can be found in the LICENSE file.
-
-library barback.test.transformer.one_to_many;
-
-import 'dart:async';
-
-import 'package:barback/barback.dart';
-
-import 'mock.dart';
-
-/// A [Transformer] that takes an input asset that contains a comma-separated
-/// list of paths and outputs a file for each path.
-class OneToManyTransformer extends MockTransformer {
-  final String extension;
-
-  /// Creates a transformer that consumes assets with [extension].
-  ///
-  /// That file contains a comma-separated list of paths and it will output
-  /// files at each of those paths.
-  OneToManyTransformer(this.extension);
-
-  bool doIsPrimary(AssetId id) => id.extension == ".$extension";
-
-  Future doApply(Transform transform) {
-    return getPrimary(transform)
-        .then((input) => input.readAsString())
-        .then((lines) {
-      for (var line in lines.split(",")) {
-        var id = new AssetId(transform.primaryInput.id.package, line);
-        transform.addOutput(new Asset.fromString(id, "spread $extension"));
-      }
-    });
-  }
-
-  String toString() => "1->many $extension";
-}