Handle `new Object()` in compile_from_dill_test

pkg/compiler/lib/src/js_emitter/metadata_collector.dart

 // Copyright (c) 2013, 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 dart2js.js_emitter.metadata_collector;
 
 import 'package:js_ast/src/precedence.dart' as js_precedence;
 
 import '../common.dart';
 import '../constants/values.dart';
@@ skipping 171 matching lines @@
   }
 
   jsAst.Fun buildLibraryMetadataFunction(LibraryEntity element) {
     if (!_mirrorsData.mustRetainMetadata ||
         !_mirrorsData.isLibraryReferencedFromMirrorSystem(element)) {
       return null;
     }
     return _buildMetadataFunction(element as LibraryElement);
   }
 
-  jsAst.Fun buildClassMetadataFunction(ClassElement element) {
+  jsAst.Fun buildClassMetadataFunction(ClassEntity cls) {
     if (!_mirrorsData.mustRetainMetadata ||
-        !_mirrorsData.isClassReferencedFromMirrorSystem(element)) {
+        !_mirrorsData.isClassReferencedFromMirrorSystem(cls)) {
       return null;
     }
+    // TODO(johnniwinther): Handle class entities.
+    ClassElement element = cls;
     return _buildMetadataFunction(element);
   }
 
   bool _mustEmitMetadataForMember(MemberElement element) {
     return _mirrorsData.mustRetainMetadata &&
         _mirrorsData.isMemberReferencedFromMirrorSystem(element);
   }
 
   jsAst.Fun buildFieldMetadataFunction(FieldElement element) {
     if (!_mustEmitMetadataForMember(element)) return null;
@@ skipping 256 matching lines @@
     if (token is _ForwardingMetadataEntry && !token.isBound) {
       _foundUnboundToken = true;
     }
   }
 
   bool findUnboundPlaceholders(jsAst.Node node) {
     node.accept(this);
     return _foundUnboundToken;
   }
 }