simplify constructors, fixes #564

test/codegen/expect/extensions.js

Index: test/codegen/expect/extensions.js
diff --git a/test/codegen/expect/extensions.js b/test/codegen/expect/extensions.js
index 099cd216c35e4ffbef73bb7bcd226f4144fbe486..9cfa8105cd720bcd7fea15f38c620abceee3e6e5 100644
--- a/test/codegen/expect/extensions.js
+++ b/test/codegen/expect/extensions.js
@@ -8,9 +8,9 @@ dart_library.library('extensions', null, /* Imports */[
   const dartx = dart_sdk.dartx;
   const extensions = Object.create(null);
   extensions.StringIterable = class StringIterable extends collection.IterableBase$(core.String) {
-    StringIterable() {
+    new() {
       this.iterator = null;
-      super.IterableBase();
+      super.new();
     }
   };
   dart.setSignature(extensions.StringIterable, {});