Fix ResynthesizerResultProvider's handling of parts.

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 'dart:developer';
 
 import 'package:analyzer/src/generated/engine.dart';
@@ skipping 43 matching lines @@
  * An [AnalysisTarget] wrapper for an [AnalysisContext].
  */
 class AnalysisContextTarget implements AnalysisTarget {
   static final AnalysisContextTarget request = new AnalysisContextTarget(null);
 
   final AnalysisContext context;
 
   AnalysisContextTarget(this.context);
 
   @override
+  Source get librarySource => null;
+
+  @override
   Source get source => null;
 }
 
 /**
  * An object with which an analysis result can be associated.
  *
  * Clients may implement this class when creating new kinds of targets.
  * Instances of this type are used in hashed data structures, so subtypes are
  * required to correctly implement [==] and [hashCode].
  */
 abstract class AnalysisTarget {
   /**
+   * If this target is associated with a library, return the source of the
+   * library's defining compilation unit; otherwise return `null`.
+   */
+  Source get librarySource;
+
+  /**
    * Return the source associated with this target, or `null` if this target is
    * not associated with a source.
    */
   Source get source;
 }
 
 /**
  * An object used to compute one or more analysis results associated with a
  * single target.
  *
@@ skipping 699 matching lines @@
   /**
    * A work should be done, but without any special urgency.
    */
   NORMAL,
 
   /**
    * Nothing to do.
    */
   NONE
 }