remove docgen source and targets from build

pkg/docgen/test/inherited_comments_test.dart

-// 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.test.inherited_comments;
-
-import 'dart:convert';
-import 'dart:io';
-
-import 'package:path/path.dart' as p;
-import 'package:scheduled_test/descriptor.dart' as d;
-import 'package:scheduled_test/scheduled_test.dart';
-
-import 'util.dart';
-import '../lib/docgen.dart' as dg;
-
-void main() {
-
-  setUp(() {
-    scheduleTempDir();
-  });
-
-  test('inherited comments', () {
-    schedule(() {
-      var codeDir = getMultiLibraryCodePath();
-      expect(FileSystemEntity.isDirectorySync(codeDir), isTrue);
-      return dg.docgen([codeDir], out: p.join(d.defaultRoot, 'docs'));
-    });
-
-    schedule(() {
-      var path = p.join(d.defaultRoot, 'docs', 'dart-core.Set.json');
-      var dartCoreSetJson = new File(path).readAsStringSync();
-
-      var dartCoreSet = JSON.decode(dartCoreSetJson) as Map<String, dynamic>;
-
-      var toListDetails = dartCoreSet['inheritedMethods']['methods']['toList']
-          as Map<String, dynamic>;
-
-      expect(toListDetails, containsPair('comment', _TO_LIST_COMMENT));
-      expect(toListDetails, containsPair('commentFrom', _TO_LIST_COMMENT_FROM));
-    });
-  });
-}
-
-const _TO_LIST_COMMENT = "<p>Creates a <a>dart:core.List</a> containing the "
-    "elements of this <a>dart:core.Iterable</a>.</p>\n<p>The elements are in "
-    "iteration order. The list is fixed-length\nif "
-    "<a>dart:core.Set.toList.growable</a> is false.</p>";
-const _TO_LIST_COMMENT_FROM = "dart:core.Iterable.toList";