ensure that lifted __esModules still expose __esModule

Author: guybedford

core/register-loader.js

@@ -612,13 +612,16 @@ function doEvaluate (loader, load, link, registry, state, seen) {
       if (module.exports !== moduleObj.default)
         moduleObj.default = module.exports;
 
-      // __esModule flag extension support
+      // __esModule flag extension support via lifting
       if (moduleObj.default && moduleObj.default.__esModule) {
         moduleObj.__useDefault = false;
         for (var p in moduleObj.default) {
           if (Object.hasOwnProperty.call(moduleObj.default, p))
             moduleObj[p] = moduleObj.default[p];
         }
+        Object.defineProperty(moduleObj, '__esModule', {
+          value: true
+        });
       }
     }
   }