Add an analysis option to disable cache flushing.

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:async';
 import 'dart:collection';
 
 import 'package:analyzer/exception/exception.dart';
@@ skipping 1211 matching lines @@
         }
       }
     }
   }
 
   /**
    * Return the [CacheFlushManager] for the given [descriptor], not `null`.
    */
   CacheFlushManager _getFlushManager(ResultDescriptor descriptor) {
     ResultCachingPolicy policy = descriptor.cachingPolicy;
-    if (identical(policy, DEFAULT_CACHING_POLICY)) {
+    if (identical(policy, DEFAULT_CACHING_POLICY) ||
+        context.analysisOptions.disableCacheFlushing) {
       return UnlimitedCacheFlushManager.INSTANCE;
     }
     CacheFlushManager manager = _flushManagerMap[policy];
     if (manager == null) {
       manager = new CacheFlushManager(policy, _isPriorityAnalysisTarget);
       _flushManagerMap[policy] = manager;
     }
     return manager;
   }
 
@@ skipping 296 matching lines @@
   void resultAccessed(TargetedResult result) {}
 
   @override
   List<TargetedResult> resultStored(TargetedResult newResult, newValue) {
     return TargetedResult.EMPTY_LIST;
   }
 
   @override
   void targetRemoved(AnalysisTarget target) {}
 }