Process handled exports correctly.

tests/compiler/dart2js/mock_compiler.dart

 // Copyright (c) 2012, 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 mock_compiler;
 
 import 'dart:uri';
 
 import '../../../sdk/lib/_internal/compiler/compiler.dart' as api;
 import '../../../sdk/lib/_internal/compiler/implementation/elements/elements.dart';
@@ skipping 127 matching lines @@
     mainApp = mockLibrary(this, "");
     initializeSpecialClasses();
     // We need to make sure the Object class is resolved. When registering a
     // dynamic invocation the ArgumentTypesRegistry eventually iterates over
     // the interfaces of the Object class which would be 'null' if the class
     // wasn't resolved.
     objectClass.ensureResolved(this);
   }
 
   /**
+   * Registers the [source] with [uri] making it possible load [source] as a
+   * library.
+   */
+  void registerSource(Uri uri, String source) {
+    sourceFiles[uri.toString()] = new MockFile(source);
+  }
+
+  /**
    * Used internally to create a library from a source text. The created library
    * is fixed to export its top-level declarations.
    */
   LibraryElement createLibrary(String name, String source) {
     Uri uri = new Uri.fromComponents(scheme: "source", path: name);
     var script = new Script(uri, new MockFile(source));
     var library = new LibraryElementX(script);
     parseScript(source, library);
     library.setExports(library.localScope.values.toList());
     return library;
@@ skipping 141 matching lines @@
   operator []=(Node node, Element element) {
     map[node] = element;
   }
 
   operator [](Node node) => map[node];
 
   void remove(Node node) {
     map.remove(node);
   }
 }