Use a more precise type for "object" in analysis server API.

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';
 
 import 'package:analysis_server/src/computer/element.dart' show
     elementFromEngine;
 import 'package:analysis_server/src/search/search_result.dart' show
     searchResultFromMatch;
 import 'package:analysis_server/src/services/correction/fix.dart' show Fix;
+import 'package:analysis_server/src/services/json.dart';
 import 'package:analysis_server/src/services/search/search_engine.dart' as
     engine;
 import 'package:analyzer/src/generated/ast.dart' as engine;
 import 'package:analyzer/src/generated/element.dart' as engine;
 import 'package:analyzer/src/generated/engine.dart' as engine;
 import 'package:analyzer/src/generated/error.dart' as engine;
 import 'package:analyzer/src/generated/source.dart' as engine;
 
 part 'generated_protocol.dart';
 
@@ skipping 1027 matching lines @@
     hash = 0x1fffffff & (hash + ((0x03ffffff & hash) << 3));
     hash = hash ^ (hash >> 11);
     return 0x1fffffff & (hash + ((0x00003fff & hash) << 15));
   }
 
   static int hash2(a, b) => finish(combine(combine(0, a), b));
 
   static int hash4(a, b, c, d) =>
       finish(combine(combine(combine(combine(0, a), b), c), d));
 }