sort classes in dependency order, or load lazily if needed, fixes #78

test/codegen/expect/dart/_js_helper.js

Index: test/codegen/expect/dart/_js_helper.js
diff --git a/test/codegen/expect/dart/_js_helper.js b/test/codegen/expect/dart/_js_helper.js
index 15b03ab6e193470a8cd816165fde74b9993e3b80..32dd607fcc3d052865e63f4b4f0e73601f349118 100644
--- a/test/codegen/expect/dart/_js_helper.js
+++ b/test/codegen/expect/dart/_js_helper.js
@@ -1343,7 +1343,7 @@ var _js_helper;
       if (result !== null)
         return dart.as(result, core.bool);
     }
-    return dart.is(object, JavaScriptIndexingBehavior);
+    return dart.is(object, exports.JavaScriptIndexingBehavior);
   }
   // Function S: (dynamic) → String
   function S(value) {
@@ -3133,8 +3133,12 @@ var _js_helper;
       throw new DeferredNotLoadedError(uri);
     }
   }
-  class JavaScriptIndexingBehavior extends _interceptors.JSMutableIndexable {
-  }
+  dart.defineLazyClass(exports, {
+    get JavaScriptIndexingBehavior() {
+      return class JavaScriptIndexingBehavior extends _interceptors.JSMutableIndexable {
+      };
+    }
+  });
   class TypeErrorImplementation extends core.Error {
     TypeErrorImplementation(value, type) {
       this.message = `type '${Primitives.objectTypeName(value)}' is not a subtype ` + `of type '${type}'`;