Context invalidation on option changes (Implements #24574).

pkg/analyzer/lib/src/context/context.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.context;
 
 import 'dart:async';
 import 'dart:collection';
 
 import 'package:analyzer/instrumentation/instrumentation.dart';
@@ skipping 397 matching lines @@
       _sourceFactory.context = null;
     }
     factory.context = this;
     _sourceFactory = factory;
     _cache = createCacheFromSourceFactory(factory);
     for (WorkManager workManager in workManagers) {
       workManager.onSourceFactoryChanged();
     }
   }
 
+  /**
+   * Invalidate analysis cache.
+   */
+  void invalidateCachedResults() {
+    _cache = createCacheFromSourceFactory(_sourceFactory);
+  }
+
   @override
   List<Source> get sources {
     return _cache.sources.toList();
   }
 
   /**
    * Return a list of the sources that would be processed by
    * [performAnalysisTask]. This method duplicates, and must therefore be kept
    * in sync with, [getNextAnalysisTask]. This method is intended to be used for
    * testing purposes only.
@@ skipping 1675 matching lines @@
         new PendingFuture<T>(_context, target, computeValue);
     if (!pendingFuture.evaluate(entry)) {
       _context._pendingFutureTargets
           .putIfAbsent(target, () => <PendingFuture>[])
           .add(pendingFuture);
       scheduleComputation();
     }
     return pendingFuture.future;
   }
 }