pkg/docgen: include all package libraries under lib/, except those under lib/src

pkg/docgen/test/generate_json_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.generate_json_test;
 
 import 'dart:io';
 
 import 'package:path/path.dart' as p;
 import 'package:scheduled_test/descriptor.dart' as d;
@@ skipping 14 matching lines @@
       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":""';