Flush memento objects.

pkg/analyzer/lib/src/context/cache.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.context.cache;
 
 import 'dart:collection';
 
 import 'package:analyzer/src/generated/engine.dart'
     show AnalysisEngine, CacheState, InternalAnalysisContext, RetentionPriority;
@@ skipping 799 matching lines @@
     state = CacheState.INVALID;
     value = descriptor.defaultValue;
   }
 
   /**
    * Flush this value.
    */
   void flush() {
     state = CacheState.FLUSHED;
     value = descriptor.defaultValue;
+    memento = null;
   }
 }
 
 /**
  * A cache partition that contains all of the targets in the SDK.
  */
 class SdkCachePartition extends CachePartition {
   /**
    * Initialize a newly created cache partition, belonging to the given
    * [context].
@@ skipping 56 matching lines @@
 class UniversalCachePartition extends CachePartition {
   /**
    * Initialize a newly created cache partition, belonging to the given
    * [context].
    */
   UniversalCachePartition(InternalAnalysisContext context) : super(context);
 
   @override
   bool contains(AnalysisTarget target) => true;
 }