Store the async-await compiled pub code directly in the repo.

sdk/lib/_internal/pub_generated/lib/src/barback/transformer_id.dart

Index: sdk/lib/_internal/pub_generated/lib/src/barback/transformer_id.dart
diff --git a/sdk/lib/_internal/pub_generated/lib/src/barback/transformer_id.dart b/sdk/lib/_internal/pub_generated/lib/src/barback/transformer_id.dart
new file mode 100644
index 0000000000000000000000000000000000000000..c209c70e8cec63d3e130130d874e1af40c0203ad
--- /dev/null
+++ b/sdk/lib/_internal/pub_generated/lib/src/barback/transformer_id.dart
@@ -0,0 +1,53 @@
+library pub.barback.transformer_id;
+import 'dart:async';
+import 'package:barback/barback.dart';
+import 'package:path/path.dart' as p;
+import 'package:source_span/source_span.dart';
+import '../io.dart';
+import '../utils.dart';
+const _BUILT_IN_TRANSFORMERS = const ['\$dart2js'];
+class TransformerId {
+  final String package;
+  final String path;
+  final SourceSpan span;
+  bool get isBuiltInTransformer => package.startsWith('\$');
+  factory TransformerId.parse(String identifier, SourceSpan span) {
+    if (identifier.isEmpty) {
+      throw new FormatException('Invalid library identifier: "".');
+    }
+    var parts = split1(identifier, "/");
+    if (parts.length == 1) {
+      return new TransformerId(parts.single, null, span);
+    }
+    return new TransformerId(parts.first, parts.last, span);
+  }
+  TransformerId(this.package, this.path, this.span) {
+    if (!package.startsWith('\$')) return;
+    if (_BUILT_IN_TRANSFORMERS.contains(package)) return;
+    throw new SourceSpanFormatException(
+        'Unsupported built-in transformer $package.',
+        span);
+  }
+  bool operator ==(other) =>
+      other is TransformerId && other.package == package && other.path == path;
+  int get hashCode => package.hashCode ^ path.hashCode;
+  String toString() => path == null ? package : '$package/$path';
+  Future<AssetId> getAssetId(Barback barback) {
+    if (path != null) {
+      return new Future.value(new AssetId(package, 'lib/$path.dart'));
+    }
+    var transformerAsset = new AssetId(package, 'lib/transformer.dart');
+    return barback.getAssetById(
+        transformerAsset).then(
+            (_) =>
+                transformerAsset).catchError(
+                    (e) => new AssetId(package, 'lib/$package.dart'),
+                    test: (e) => e is AssetNotFoundException);
+  }
+  String getFullPath(String packageDir) {
+    if (path != null) return p.join(packageDir, 'lib', p.fromUri('$path.dart'));
+    var transformerPath = p.join(packageDir, 'lib', 'transformer.dart');
+    if (fileExists(transformerPath)) return transformerPath;
+    return p.join(packageDir, 'lib', '$package.dart');
+  }
+}