Add simple Dart tasks

pkg/analyzer/lib/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.task.model;
 
 import 'dart:collection';
 
 import 'package:analyzer/src/generated/engine.dart' hide AnalysisTask;
 import 'package:analyzer/src/generated/java_engine.dart';
@@ skipping 233 matching lines @@
   factory TaskDescriptor(String name, BuildTask buildTask,
       CreateTaskInputs inputBuilder, List<ResultDescriptor> results) =
       TaskDescriptorImpl;
 
   /**
    * Return the builder used to build the inputs to the task.
    */
   CreateTaskInputs get createTaskInputs;
 
   /**
+   * Return the name of the task being described.
+   */
+  String get name;
+
+  /**
    * Return a list of the analysis results that will be computed by this task.
    */
   List<ResultDescriptor> get results;
 
   /**
    * Create and return a task that is described by this descriptor that can be
    * used to compute results based on the given [inputs].
    */
   AnalysisTask createTask(AnalysisContext context, AnalysisTarget target,
       Map<String, dynamic> inputs);
@@ skipping 63 matching lines @@
    * be computed, or `false` if the inputs have been computed.
    *
    * It is safe to invoke [moveNext] after it has returned `false`. In this case
    * [moveNext] has no effect and will again return `false`.
    *
    * Throws a [StateError] if the value of the current result has not been
    * provided using [currentValue].
    */
   bool moveNext();
 }