Resolve class element of Object, even if no objects are used.

frog/leg/resolver.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.
 
 interface TreeElements {
   Element operator[](Node node);
   Selector getSelector(Send send);
 }
 
 class TreeElementMapping implements TreeElements {
@@ skipping 1007 matching lines @@
     compiler.ensure(element !== null);
     compiler.ensure(!element.isResolved);
     element.supertype = visit(node.superclass);
     if (element.name != Types.OBJECT && element.supertype === null) {
       ClassElement objectElement = context.lookup(Types.OBJECT);
       if (objectElement !== null && !objectElement.isResolved) {
         compiler.resolver.toResolve.add(objectElement);
       } else if (objectElement === null){
         error(node, MessageKind.CANNOT_RESOLVE_TYPE, [Types.OBJECT]);
       }
-      element.supertype = new SimpleType(Types.OBJECT,
-                                         objectElement);
+      element.supertype = new SimpleType(Types.OBJECT, objectElement);
     }
     if (node.defaultClause !== null) {
       element.defaultClass = visit(node.defaultClause.nodes.head);
     }
     for (Link<Node> link = node.interfaces.nodes;
          !link.isEmpty();
          link = link.tail) {
       element.interfaces = element.interfaces.prepend(visit(link.head));
     }
     return element.computeType(compiler);
@@ skipping 252 matching lines @@
 class TopScope extends Scope {
   LibraryElement get library() => element;
 
   TopScope(LibraryElement library) : super(null, library);
   Element lookup(SourceString name) => library.find(name);
 
   Element add(Element element) {
     throw "Cannot add an element in the top scope";
   }
 }