Add constructors to signatures

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 4cf8d2f333e4dd419218d7a9d0d239731ad3d299..4cf84784da2f49bf2549764e39fc86fb0a7fea3a 100644
--- a/test/codegen/expect/sunflower/dom.js
+++ b/test/codegen/expect/sunflower/dom.js
@@ -8,10 +8,16 @@ var core = dart.import(core);
       this.name = name;
     }
   }
+  dart.setSignature(JsName, {
+    constructors: () => ({JsName: [JsName, [], {am: core.String}]})
+  });
   class Overload extends core.Object {
     Overload() {
     }
   }
+  dart.setSignature(Overload, {
+    constructors: () => ({Overload: [Overload, []]})
+  });
   let overload = dart.const(new Overload());
   let EventListener = dart.typedef('EventListener', () => dart.functionType(dart.void, [Event]));
   class Event extends core.Object {}