Add back MDN comments.

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 1530 matching lines @@
       var mdnPath = path.join(root, 'utils/apidoc/mdn/database.json');
       var mdnFile = new File(mdnPath);
       if (mdnFile.existsSync()) {
         Indexable._mdn = JSON.decode(mdnFile.readAsStringSync());
       } else {
         _Generator.logger.warning("Cannot find MDN docs expected at $mdnPath");
         Indexable._mdn = {};
       }
     }
     var domAnnotation = this.annotations.firstWhere(
-        (e) => e.mirror.qualifiedName == 'metadata.DomName',
+        (e) => e.mirror.qualifiedName == #metadata.DomName,
         orElse: () => null);
     if (domAnnotation == null) return '';
     var domName = domAnnotation.parameters.single;
     var parts = domName.split('.');
     if (parts.length == 2) return _mdnMemberComment(parts[0], parts[1]);
     if (parts.length == 1) return _mdnTypeComment(parts[0]);
   }
 
   String get packagePrefix => owner.packagePrefix;
 }
@@ skipping 602 matching lines @@
         .map((e) => originalMirror.getField(e.simpleName).reflectee)
         .where((e) => e != null)
         .toList();
   }
 
   Map toMap() => {
     'name': Indexable.getDocgenObject(mirror, owningLibrary).docName,
     'parameters': parameters
   };
 }