Handle redirects to unresolved redirects

pkg/compiler/lib/src/serialization/equivalence.dart

 // Copyright (c) 2016, 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.
 
 /// Functions for asserting equivalence across serialization.
 
 library dart2js.serialization.equivalence;
 
 import '../closure.dart';
 import '../common.dart';
@@ skipping 498 matching lines @@
     return visit(element1.exportedLibrary, element2.exportedLibrary) &&
         visit(element1.library, element2.library);
   }
 
   @override
   bool visitPrefixElement(PrefixElement element1, PrefixElement element2) {
     return strategy.test(
             element1, element2, 'name', element1.name, element2.name) &&
         visit(element1.library, element2.library);
   }
+
+  @override
+  bool visitErroneousElement(
+      ErroneousElement element1, ErroneousElement element2) {
+    return strategy.test(element1, element2, 'messageKind',
+        element1.messageKind, element2.messageKind);
+  }
 }
 
 /// Visitor that checks for equivalence of [DartType]s.
 class TypeEquivalence implements DartTypeVisitor<bool, DartType> {
   final TestStrategy strategy;
 
   const TypeEquivalence([this.strategy = const TestStrategy()]);
 
   bool visit(DartType type1, DartType type2) {
     return strategy.test(type1, type2, 'kind', type1.kind, type2.kind) &&
@@ skipping 1307 matching lines @@
 }
 
 bool areMetadataAnnotationsEquivalent(
     MetadataAnnotation metadata1, MetadataAnnotation metadata2) {
   if (metadata1 == metadata2) return true;
   if (metadata1 == null || metadata2 == null) return false;
   return areElementsEquivalent(
           metadata1.annotatedElement, metadata2.annotatedElement) &&
       areConstantsEquivalent(metadata1.constant, metadata2.constant);
 }