Issue 26044. Cache and use LibraryElementImpl.exportNamespace.

pkg/analyzer/lib/src/generated/incremental_resolver.dart

 // Copyright (c) 2014, 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.generated.incremental_resolver;
 
 import 'dart:collection';
 import 'dart:math' as math;
 
 import 'package:analyzer/dart/ast/ast.dart';
@@ skipping 860 matching lines @@
    * The delta between [updateEndNew] and [updateEndOld].
    */
   final int updateDelta;
 
   IncrementalBodyDelta(Source source, this.updateOffset, this.updateEndOld,
       this.updateEndNew, this.updateDelta)
       : super(source);
 
   @override
   DeltaResult validate(InternalAnalysisContext context, AnalysisTarget target,
-      ResultDescriptor descriptor) {
+      ResultDescriptor descriptor, CacheState state, Object value) {
     // A body change delta should never leak outside its source.
     // It can cause invalidation of results (e.g. hints) in other sources,
     // but only when a result in the updated source is INVALIDATE_NO_DELTA.
     if (target.source != source) {
       return DeltaResult.STOP;
     }
     // don't invalidate results of standard Dart tasks
     bool isByTask(TaskDescriptor taskDescriptor) {
       return taskDescriptor.results.contains(descriptor);
     }
@@ skipping 1326 matching lines @@
   @override
   String toString() => name;
 }
 
 class _TokenPair {
   final _TokenDifferenceKind kind;
   final Token oldToken;
   final Token newToken;
   _TokenPair(this.kind, this.oldToken, this.newToken);
 }