Use Uris for corelibOrder

lib/src/codegen/module_builder.dart

Index: lib/src/codegen/module_builder.dart
diff --git a/lib/src/codegen/module_builder.dart b/lib/src/codegen/module_builder.dart
index 22cc87126c6e11c52ec92b5892d413f0294bc2b5..e34efc87b445aa35290a41e2218b4d49777863cb 100644
--- a/lib/src/codegen/module_builder.dart
+++ b/lib/src/codegen/module_builder.dart
@@ -154,9 +154,9 @@ class ES6ModuleBuilder extends ModuleBuilder {
         moduleStatements
             .add(js.statement('#.# = #;', [exportsVar, exportName, name]));
       });
-      moduleStatements
-          .add(new JS.ExportDeclaration(exportsVar, isDefault: true));
     }
+    moduleStatements
+        .add(new JS.ExportDeclaration(exportsVar, isDefault: true));
     // TODO(ochafik): What to do with jsModuleValue?
     return new JS.Program(moduleStatements);
   }