Several new features and improvements for dartdoc.

lib/json/json.dart

 // Copyright (c) 2011, 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("json");
+#library("dart:json");
 
 // Pure Dart implementation of JSON protocol.
 
 /**
  * Utility class to parse JSON and serialize objects to JSON.
  */
 class JSON {
   /**
    * Parses [json] and build the corresponding object.
    */
@@ skipping 530 matching lines @@
         first = false;
       });
       _sb.add('}');
       _seen.removeLast();
       return;
     } else {
       throw const JsonUnsupportedObjectType();
     }
   }
 }