Revert "Store actual Reference(s) for additional exports."

pkg/kernel/lib/import_table.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 kernel.import_table;
 
 import 'ast.dart';
 import 'package:path/path.dart' as path;
 
 abstract class ImportTable {
   int getImportIndex(Library library);
@@ skipping 84 matching lines @@
       throw '$referenceUri cannot refer to application library $targetUri';
     } else {
       table.addImport(target, target.importUri.toString());
     }
   }
 
   visitClassReference(Class node) {
     addLibraryImport(node.enclosingLibrary);
   }
 
-  visitLibrary(Library node) {
-    super.visitLibrary(node);
-    for (Reference exportedReference in node.additionalExports) {
-      addLibraryImport(exportedReference.node.parent);
-    }
-  }
-
   defaultMemberReference(Member node) {
     addLibraryImport(node.enclosingLibrary);
   }
 
   visitName(Name name) {
     if (name.library != null) {
       addLibraryImport(name.library);
     }
   }
 }