Add back Reflectable annotations.

pkg/docgen/lib/docgen.dart

 // Copyright (c) 2013, 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.
 
 /// **docgen** is a tool for creating machine readable representations of Dart
 /// code metadata, including: classes, members, comments and annotations.
 ///
 /// docgen is run on a `.dart` file or a directory containing `.dart` files.
 ///
 ///      $ dart docgen.dart [OPTIONS] [FILE/DIR]
@@ skipping 23 matching lines @@
 import '../../../sdk/lib/_internal/compiler/implementation/source_file_provider.dart';
 import '../../../sdk/lib/_internal/libraries.dart';
 
 var logger = new Logger('Docgen');
 
 const String USAGE = 'Usage: dart docgen.dart [OPTIONS] fooDir/barFile';
 
 
 List<String> skippedAnnotations = const [
     'metadata.DocsEditable', '_js_helper.JSName', '_js_helper.Creates',
-    '_js_helper.Returns', 'observe-src-metadata.Reflectable'];
+    '_js_helper.Returns'];
 
 /// Set of libraries declared in the SDK, so libraries that can be accessed
 /// when running dart by default.
 Iterable<LibraryMirror> _sdkLibraries;
 
 /// The dart:core library, which contains all types that are always available
 /// without import.
 LibraryMirror _coreLibrary;
 
 /// Current library being documented to be used for comment links.
@@ skipping 1341 matching lines @@
 /// Remove statics from the map of inherited items before adding them.
 Map _filterStatics(Map items) {
   var result = {};
   items.forEach((name, item) {
     if (!item.isStatic) {
       result[name] = item;
     }
   });
   return result;
 }