Don't re-export hidden members.

pkg/front_end/lib/src/fasta/source/source_loader.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.
 
 library fasta.source_loader;
 
 import 'dart:async' show Future;
 
 import 'dart:typed_data' show Uint8List;
 
@@ skipping 213 matching lines @@
       }
       for (Export export in exported.exporters) {
         exported.exportScope.forEach(export.addToExportScope);
       }
     }
     bool wasChanged = false;
     do {
       wasChanged = false;
       for (SourceLibraryBuilder exported in both) {
         for (Export export in exported.exporters) {
-          SourceLibraryBuilder exporter = export.exporter;
           exported.exportScope.forEach((String name, Builder member) {
-            if (exporter.addToExportScope(name, member)) {
+            if (export.addToExportScope(name, member)) {
               wasChanged = true;
             }
           });
         }
       }
     } while (wasChanged);
     builders.forEach((Uri uri, LibraryBuilder library) {
       if (library is SourceLibraryBuilder) {
         library.addImportsToScope();
       }
@@ skipping 305 matching lines @@
   Expression throwCompileConstantError(Expression error) {
     return target.backendTarget.throwCompileConstantError(coreTypes, error);
   }
 
   Expression buildCompileTimeError(Message message, int offset, Uri uri) {
     String text = target.context
         .format(message.withLocation(uri, offset), Severity.error);
     return target.backendTarget.buildCompileTimeError(coreTypes, text, offset);
   }
 }