remove docgen source and targets from build

pkg/docgen/test/generate_json_test.dart

Index: pkg/docgen/test/generate_json_test.dart
diff --git a/pkg/docgen/test/generate_json_test.dart b/pkg/docgen/test/generate_json_test.dart
deleted file mode 100644
index c22ae13a264de4f420c3f4dd0b4a818ab2a8bf20..0000000000000000000000000000000000000000
--- a/pkg/docgen/test/generate_json_test.dart
+++ /dev/null
@@ -1,50 +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.generate_json_test;
-
-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('json output', () {
-    schedule(() {
-      var codeDir = getMultiLibraryCodePath();
-      expect(FileSystemEntity.isDirectorySync(codeDir), isTrue);
-      return dg.docgen([codeDir], out: p.join(d.defaultRoot, 'docs'));
-    });
-
-    d.dir('docs', [
-        d.matcherFile('index.json', isJsonMap),
-        d.matcherFile('index.txt', hasSortedLines),
-        d.matcherFile('library_list.json', isJsonMap),
-        d.matcherFile('library_list.json',
-            startsWith(_LIBRARY_LIST_UNINDENT_START)),
-        d.matcherFile('sub_lib.json', isJsonMap),
-        d.matcherFile('sub_lib.SubLibClass.json', isJsonMap),
-        d.matcherFile('sub_lib.SubLibPart.json', isJsonMap),
-        d.matcherFile('test_lib-bar.C.json', isJsonMap),
-        d.matcherFile('test_lib-bar.json', isJsonMap),
-        d.matcherFile('test_lib-foo.B.json', isJsonMap),
-        d.matcherFile('test_lib-foo.json', isJsonMap),
-        d.matcherFile('test_lib.A.json', isJsonMap),
-        d.matcherFile('test_lib.B.json', isJsonMap),
-        d.matcherFile('test_lib.C.json', isJsonMap),
-        d.matcherFile('test_lib.json', isJsonMap),
-    ]).validate();
-  });
-}
-
-const _LIBRARY_LIST_UNINDENT_START = '{"libraries":[{"packageName":""';