dart2js cleanup: remove unused imports and variables

pkg/compiler/lib/src/serialization/modelz.dart

Index: pkg/compiler/lib/src/serialization/modelz.dart
diff --git a/pkg/compiler/lib/src/serialization/modelz.dart b/pkg/compiler/lib/src/serialization/modelz.dart
index b34f787af495ddf812127d047571bba43e0a6172..5bcb4a604b25947b2b0c7745d96fd31dc33e6248 100644
--- a/pkg/compiler/lib/src/serialization/modelz.dart
+++ b/pkg/compiler/lib/src/serialization/modelz.dart
@@ -13,23 +13,21 @@ import '../common.dart';
 import '../common/resolution.dart' show Resolution;
 import '../constants/constructors.dart';
 import '../constants/expressions.dart';
-import '../core_types.dart';
 import '../dart_types.dart';
+import '../elements/common.dart';
 import '../elements/elements.dart';
 import '../elements/modelx.dart' show FunctionSignatureX;
-import '../elements/common.dart';
 import '../elements/visitor.dart';
 import '../io/source_file.dart';
 import '../ordered_typeset.dart';
 import '../resolution/class_members.dart' as class_members;
-import '../resolution/tree_elements.dart' show TreeElements;
 import '../resolution/scope.dart' show Scope;
+import '../resolution/tree_elements.dart' show TreeElements;
 import '../script.dart';
 import '../serialization/constant_serialization.dart';
 import '../tokens/token.dart' show Token;
 import '../tree/tree.dart';
 import '../util/util.dart' show Link, LinkBuilder;
-
 import 'keys.dart';
 import 'serialization.dart';