Stop defensively copying AST structures before resolution

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 11 matching lines @@
   /**
    * Initialize a newly created analysis result to have the given [name] and
    * [defaultValue]. If a [cachingPolicy] is provided, it will control how long
    * values associated with this result will remain in the cache.
    */
   ListResultDescriptorImpl(String name, List<E> defaultValue,
       {ResultCachingPolicy<List<E>> cachingPolicy: DEFAULT_CACHING_POLICY})
       : super(name, defaultValue, cachingPolicy: cachingPolicy);
 
   @override
-  ListTaskInput<E> of(AnalysisTarget target) =>
-      new ListTaskInputImpl<E>(target, this);
+  ListTaskInput<E> of(AnalysisTarget target, {bool flushOnAccess: false}) {
+    if (flushOnAccess) {
+      throw new StateError('Cannot flush a list of values');
+    }
+    return new ListTaskInputImpl<E>(target, this);
+  }
 }
 
 /**
  * A concrete implementation of a [ResultDescriptor].
  */
 class ResultDescriptorImpl<V> implements ResultDescriptor<V> {
   static int _NEXT_HASH = 0;
 
   @override
   final hashCode = _NEXT_HASH++;
@@ skipping 20 matching lines @@
    */
   ResultDescriptorImpl(this.name, this.defaultValue,
       {this.cachingPolicy: DEFAULT_CACHING_POLICY});
 
   @override
   bool operator ==(Object other) {
     return other is ResultDescriptorImpl && other.hashCode == hashCode;
   }
 
   @override
-  TaskInput<V> of(AnalysisTarget target) =>
-      new SimpleTaskInput<V>(target, this);
+  TaskInput<V> of(AnalysisTarget target, {bool flushOnAccess: false}) =>
+      new SimpleTaskInput<V>(target, this, flushOnAccess: flushOnAccess);
 
   @override
   String toString() => name;
 }
 
 /**
  * A simple [ResultCachingPolicy] implementation that consider all the objects
  * to be of the size `1`.
  */
 class SimpleResultCachingPolicy<T> implements ResultCachingPolicy<T> {
@@ skipping 48 matching lines @@
   AnalysisTask createTask(AnalysisContext context, AnalysisTarget target,
       Map<String, dynamic> inputs) {
     AnalysisTask task = buildTask(context, target);
     task.inputs = inputs;
     return task;
   }
 
   @override
   String toString() => name;
 }