canonicalize const

test/codegen/expect/sunflower/dom.js

Index: test/codegen/expect/sunflower/dom.js
diff --git a/test/codegen/expect/sunflower/dom.js b/test/codegen/expect/sunflower/dom.js
index accd3b1e5ea0bec03a406ba4626e23aeeb2bd8d0..24824110499cf6579f95adddf050d4c509092119 100644
--- a/test/codegen/expect/sunflower/dom.js
+++ b/test/codegen/expect/sunflower/dom.js
@@ -11,7 +11,7 @@ var dom;
     Overload() {
     }
   }
-  let overload = new Overload();
+  let overload = dart.const(new Overload());
   let EventListener = dart.typedef('EventListener', () => dart.functionType(dart.void, [Event]));
   class Event extends core.Object {}
   let InputElement = HTMLInputElement;