remove docgen source and targets from build

pkg/docgen/test/method_param_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.method_param;
-
-import 'package:path/path.dart' as path;
-import 'package:scheduled_test/scheduled_test.dart';
-
-import 'util.dart';
-import '../lib/docgen.dart' as gen;
-
-void main() {
-  test('method function parameters', () {
-    var lib_file = path.toUri(path.join(getMultiLibraryCodePath(), 'lib',
-        'test_lib2.dart'));
-    return gen.getMirrorSystem([lib_file], false)
-      .then((mirrorSystem) {
-        var library = new gen.Library(mirrorSystem.libraries[lib_file]);
-
-        // Test that libraries do recursive exports correctly.
-        var funcParams = library.functions['fooFunc'].parameters;
-        expect('Symbol("dart.core.int")', library.functions['fooFunc']
-            .parameters['fooFuncParam'].functionDeclaration.parameters['x']
-            .type.mirror.qualifiedName.toString());
-      });
-  });
-}