Reset AnalysisDriver on priority sources changes.

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/error.dart' show AnalysisError;
@@ skipping 573 matching lines @@
    * Return a list of all of the errors associated with the given [source].
    * The list of errors will be empty if the source is not known to the context
    * or if there are no errors in the source. The errors contained in the list
    * can be incomplete.
    */
   List<AnalysisError> getErrors(Source source);
 
   /**
    * Return the next [TargetedResult] that this work manager wants to be
    * computed, or `null` if this manager doesn't need any new results.
+   *
+   * Note, that it is not guaranteed that this result will be computed, it is
+   * up to the work manager to check whether the result is already computed
+   * (for example during the next [getNextResult] invocation) or computation
+   * of the same result should be requested again.
    */
   TargetedResult getNextResult();
 
   /**
    * Return the priority if the next work order this work manager want to be
    * computed. The [AnalysisDriver] will perform the work order with
    * the highest priority.
    *
    * Even if the returned value is [WorkOrderPriority.NONE], it still does not
    * guarantee that [getNextResult] will return not `null`.
@@ skipping 37 matching lines @@
   /**
    * A work should be done, but without any special urgency.
    */
   NORMAL,
 
   /**
    * Nothing to do.
    */
   NONE
 }