Serialize exports scopes.

pkg/front_end/lib/src/fasta/dill/dill_loader.dart

Index: pkg/front_end/lib/src/fasta/dill/dill_loader.dart
diff --git a/pkg/front_end/lib/src/fasta/dill/dill_loader.dart b/pkg/front_end/lib/src/fasta/dill/dill_loader.dart
index 0ce8967160a4779b15c4a0af7e47500875572194..6b0f7af222b679941172c5da16d70e021e9d5b75 100644
--- a/pkg/front_end/lib/src/fasta/dill/dill_loader.dart
+++ b/pkg/front_end/lib/src/fasta/dill/dill_loader.dart
@@ -8,6 +8,8 @@ import 'dart:async' show Future;
 
 import 'package:kernel/ast.dart' show Library, Program, Source;
 
+import '../kernel/kernel_builder.dart' show LibraryBuilder;
+
 import '../loader.dart' show Loader;
 
 import '../problems.dart' show unhandled;
@@ -55,4 +57,11 @@ class DillLoader extends Loader<Library> {
   Future<Null> buildBody(DillLibraryBuilder builder) {
     return buildOutline(builder);
   }
+
+  void finalizeExports() {
+    builders.forEach((Uri uri, LibraryBuilder builder) {
+      DillLibraryBuilder library = builder;
+      library.finalizeExports();
+    });
+  }
 }