Serialize exports scopes.

pkg/front_end/lib/src/fasta/source/source_library_builder.dart

Index: pkg/front_end/lib/src/fasta/source/source_library_builder.dart
diff --git a/pkg/front_end/lib/src/fasta/source/source_library_builder.dart b/pkg/front_end/lib/src/fasta/source/source_library_builder.dart
index 162005275381264723e78ae382a7f3f7f62cf6e4..4857816b51f2cbf0c79567e1f78924164882def7 100644
--- a/pkg/front_end/lib/src/fasta/source/source_library_builder.dart
+++ b/pkg/front_end/lib/src/fasta/source/source_library_builder.dart
@@ -17,6 +17,7 @@ import '../builder/builder.dart'
         ConstructorReferenceBuilder,
         FormalParameterBuilder,
         FunctionTypeBuilder,
+        InvalidTypeBuilder,
         LibraryBuilder,
         MemberBuilder,
         MetadataBuilder,
@@ -96,6 +97,12 @@ abstract class SourceLibraryBuilder<T extends TypeBuilder, R>
 
   bool canAddImplementationBuilders = false;
 
+  /// Exports in addition to the members declared in this library.
+  ///
+  /// See [../dill/dill_library_builder.dart] for additional details on the
+  /// format used.
+  List<List<String>> additionalExports;
+
   SourceLibraryBuilder(SourceLoader loader, Uri fileUri)
       : this.fromScopes(loader, fileUri, new DeclarationBuilder<T>.library(),
             new Scope.top());
@@ -512,6 +519,19 @@ abstract class SourceLibraryBuilder<T extends TypeBuilder, R>
         addToScope(name, member, -1, true);
       });
     }
+    exportScope.forEach((String name, Builder member) {
+      if (member.parent != this) {
+        additionalExports ??= <List<String>>[];
+        Builder parent = member.parent;
+        if (parent is LibraryBuilder) {
+          additionalExports.add(<String>["${parent.uri}", name]);
+        } else {
+          InvalidTypeBuilder invalidType = member;
+          String message = invalidType.message.message;
+          additionalExports.add(<String>[null, name, message]);
+        }
+      }
+    });
   }
 
   @override