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

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

Index: pkg/compiler/lib/src/js_backend/codegen/js_tree_builder.dart
diff --git a/pkg/compiler/lib/src/js_backend/codegen/js_tree_builder.dart b/pkg/compiler/lib/src/js_backend/codegen/js_tree_builder.dart
index b21bb5e13759296d74005dbebde37ff1e0812cc9..9b8ed20602d9d136c9934d873d50e7896c6d9d13 100644
--- a/pkg/compiler/lib/src/js_backend/codegen/js_tree_builder.dart
+++ b/pkg/compiler/lib/src/js_backend/codegen/js_tree_builder.dart
@@ -64,8 +64,8 @@ class JsTreeBuilder extends Builder {
     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());
   }