Get memento objects from tasks, remember in cache and pass back to tasks.

pkg/analyzer/lib/src/task/model.dart

 // Copyright (c) 2015, 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 analyzer.src.task.model;
 
 import 'package:analyzer/src/generated/engine.dart' hide AnalysisTask;
 import 'package:analyzer/src/task/inputs.dart';
 import 'package:analyzer/task/model.dart';
 
@@ skipping 103 matching lines @@
    * Initialize a newly created task descriptor to have the given [name] and to
    * describe a task that takes the inputs built using the given [createTaskInputs],
    * and produces the given [results]. The [buildTask] will be used to create
    * the instance of [AnalysisTask] thusly described.
    */
   TaskDescriptorImpl(
       this.name, this.buildTask, this.createTaskInputs, this.results);
 
   @override
   AnalysisTask createTask(AnalysisContext context, AnalysisTarget target,
-      Map<String, dynamic> inputs) {
+      Map<String, dynamic> inputs, dynamic inputMemento) {
     AnalysisTask task = buildTask(context, target);
     task.inputs = inputs;
+    task.inputMemento = inputMemento;
     return task;
   }
 
   @override
   String toString() => name;
 }