Handle symbol literals in closed_world2_test

tests/compiler/dart2js/mock_compiler.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 mock_compiler;
 
 import 'dart:async';
 import 'dart:collection';
 
 import 'package:compiler/compiler_new.dart' as api;
@@ skipping 92 matching lines @@
                 preserveComments: preserveComments,
                 trustTypeAnnotations: trustTypeAnnotations,
                 trustJSInteropTypeAnnotations: trustJSInteropTypeAnnotations,
                 shownPackageWarnings: const []),
             outputProvider: outputProvider) {
     deferredLoadTask = new MockDeferredLoadTask(this);
 
     registerSource(
         Uris.dart_core, buildLibrarySource(DEFAULT_CORE_LIBRARY, coreSource));
     registerSource(PATCH_CORE, DEFAULT_PATCH_CORE_SOURCE);
+    registerSource(
+        Uris.dart__internal, buildLibrarySource(DEFAULT_INTERNAL_LIBRARY));
 
     registerSource(
         Uris.dart__js_helper, buildLibrarySource(DEFAULT_JS_HELPER_LIBRARY));
     registerSource(Uris.dart__foreign_helper,
         buildLibrarySource(DEFAULT_FOREIGN_HELPER_LIBRARY));
     registerSource(Uris.dart__interceptors,
         buildLibrarySource(DEFAULT_INTERCEPTORS_LIBRARY));
     registerSource(Uris.dart__isolate_helper,
         buildLibrarySource(DEFAULT_ISOLATE_HELPER_LIBRARY));
     registerSource(Uris.dart_mirrors, DEFAULT_MIRRORS_SOURCE);
@@ skipping 269 matching lines @@
       trustTypeAnnotations: trustTypeAnnotations,
       enableTypeAssertions: enableTypeAssertions,
       enableUserAssertions: enableUserAssertions,
       expectedErrors: expectedErrors,
       expectedWarnings: expectedWarnings,
       outputProvider: outputProvider);
   compiler.registerSource(uri, code);
   compiler.diagnosticHandler = createHandler(compiler, code);
   return compiler;
 }