Issue 25095. Add 'Change X to Y type annotation' Quick Fix.

pkg/analysis_server/lib/src/services/correction/fix.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 analysis_server.src.services.correction.fix;
 
 import 'dart:async';
 
 import 'package:analysis_server/plugin/edit/fix/fix_core.dart';
 import 'package:analysis_server/src/plugin/server_plugin.dart';
@@ skipping 109 matching lines @@
       'ADD_PACKAGE_DEPENDENCY', 50, "Add dependency on package '{0}'");
   static const ADD_PART_OF =
       const FixKind('ADD_PART_OF', 50, "Add 'part of' directive");
   static const ADD_SUPER_CONSTRUCTOR_INVOCATION = const FixKind(
       'ADD_SUPER_CONSTRUCTOR_INVOCATION',
       50,
       "Add super constructor {0} invocation");
   static const CHANGE_TO = const FixKind('CHANGE_TO', 49, "Change to '{0}'");
   static const CHANGE_TO_STATIC_ACCESS = const FixKind(
       'CHANGE_TO_STATIC_ACCESS', 50, "Change access to static using '{0}'");
+  static const CHANGE_TYPE_ANNOTATION = const FixKind(
+      'CHANGE_TYPE_ANNOTATION', 50, "Change '{0}' to '{1}' type annotation");
   static const CREATE_CLASS =
       const FixKind('CREATE_CLASS', 50, "Create class '{0}'");
   static const CREATE_CONSTRUCTOR =
       const FixKind('CREATE_CONSTRUCTOR', 50, "Create constructor '{0}'");
   static const CREATE_CONSTRUCTOR_FOR_FINAL_FIELDS = const FixKind(
       'CREATE_CONSTRUCTOR_FOR_FINAL_FIELDS',
       50,
       "Create constructor for final fields");
   static const CREATE_CONSTRUCTOR_SUPER = const FixKind(
       'CREATE_CONSTRUCTOR_SUPER', 50, "Create constructor to call {0}");
@@ skipping 81 matching lines @@
   @override
   final AnalysisError error;
 
   FixContextImpl(this.resourceProvider, this.analysisContext, this.error);
 
   FixContextImpl.from(FixContext other)
       : resourceProvider = other.resourceProvider,
         analysisContext = other.analysisContext,
         error = other.error;
 }