more progress implementing analysis server code completion

pkg/analysis_server/lib/src/protocol.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 protocol;
 
 import 'dart:collection';
 import 'dart:convert' show JsonDecoder;
 
-import 'package:analysis_server/src/collections.dart';
+import 'package:analysis_services/json.dart';
 
 /**
  * An abstract enumeration.
  */
 abstract class Enum2<E extends Enum2> implements Comparable<E> {
   /**
    * The name of this enum constant, as declared in the enum declaration.
    */
   final String name;
 
@@ skipping 904 matching lines @@
  */
 _toJson(Object value) {
   if (value is HasToJson) {
     return value.toJson();
   }
   if (value is Iterable) {
     return value.map((item) => _toJson(item)).toList();
   }
   return value;
 }