Implement constructor bodies and initializers in CPS->JS backend.

pkg/compiler/lib/src/js_backend/codegen/js_tree_builder.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 js_tree_ir_builder;
 
 import '../../tree_ir/tree_ir_builder.dart' show Builder;
 import 'glue.dart' show Glue;
 import '../../dart2jslib.dart' show Selector, InternalErrorFunction;
 import '../../elements/elements.dart';
@@ skipping 46 matching lines @@
     return new SetField(getVariableReference(node.object),
                         node.field,
                         getVariableReference(node.value),
                         visit(node.body));
   }
 
   Expression visitCreateBox(cps_ir.CreateBox node) {
     return new CreateBox();
   }
 
-  Expression visitCreateClosureClass(cps_ir.CreateClosureClass node) {
-    return new CreateClosureClass(
+  Expression visitCreateInstance(cps_ir.CreateInstance node) {
+    return new CreateInstance(
         node.classElement,
         node.arguments.map(getVariableReference).toList());
   }
 }