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

frog/leg/resolver.dart

Index: frog/leg/resolver.dart
diff --git a/frog/leg/resolver.dart b/frog/leg/resolver.dart
index aaf42427d81ab3d84b03ab21d97f2bd0aef7b3ce..1ed0cb449ee59a5fb557d0eb3f7855d1cbd1b3c2 100644
--- a/frog/leg/resolver.dart
+++ b/frog/leg/resolver.dart
@@ -1025,8 +1025,7 @@ class ClassResolverVisitor extends CommonResolverVisitor<Type> {
       } 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);