remove docgen source and targets from build

pkg/docgen/lib/src/models/generic.dart

Index: pkg/docgen/lib/src/models/generic.dart
diff --git a/pkg/docgen/lib/src/models/generic.dart b/pkg/docgen/lib/src/models/generic.dart
deleted file mode 100644
index 46a48a11b35e96e8f899d95c3e2f31f059e753b3..0000000000000000000000000000000000000000
--- a/pkg/docgen/lib/src/models/generic.dart
+++ /dev/null
@@ -1,22 +0,0 @@
-// Copyright (c) 2014, 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 docgen.models.generic;
-
-import '../exports/source_mirrors.dart';
-import '../exports/mirrors_util.dart' as dart2js_util;
-
-import 'mirror_based.dart';
-
-/// A Docgen wrapper around the dart2js mirror for a generic type.
-class Generic extends MirrorBased<TypeVariableMirror> {
-  final TypeVariableMirror mirror;
-
-  Generic(this.mirror);
-
-  Map toMap() => {
-    'name': dart2js_util.nameOf(mirror),
-    'type': dart2js_util.qualifiedNameOf(mirror.upperBound)
-  };
-}