Generative constructors in the new dart backend.

pkg/compiler/lib/src/js_backend/codegen/codegen.dart

 // Copyright (c) 2014, 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 code_generator;
 
 import 'glue.dart';
 
 import '../../tree_ir/tree_ir_nodes.dart' as tree_ir;
 import '../../js/js.dart' as js;
@@ skipping 398 matching lines @@
   void visitWhileTrue(tree_ir.WhileTrue node) {
     accumulator.add(
         buildWhile(new js.LiteralBool(true), node.body, node.label, node));
   }
 
   @override
   void visitReturn(tree_ir.Return node) {
     accumulator.add(new js.Return(visitExpression(node.value)));
   }
 
+  @override
+  js.Expression visitFieldInitializer(tree_ir.FieldInitializer node) {
+    return giveup(node);
+    // TODO: implement FieldInitializer
+  }
+
+  @override
+  js.Expression visitSuperInitializer(tree_ir.SuperInitializer node) {
+    return giveup(node);
+    // TODO: implement SuperInitializer
+  }
+
 }