fixing node-chakracore after taking integration

lib/internal/bootstrap/node.js

@@ -33,16 +33,22 @@
       // This file contains the V8-specific "%<function>" syntax for accessing
       // private functions. This is not supported on ChakraCore and causes a
       // parser failure. Inject a cache entry to prevent the file from being
-      // parsed. Return an array to mimic behavior (required by util.inspect)
+      // parsed. Return an array to mimic behavior (required by util.inspect).
+      //
+      // TODO:  below methods need to be implemented to return correct values!
       NativeModule._cache['internal/v8'] = {
         loaded: true,
         exports: {
           previewMapIterator: function() { return []; },
           previewSetIterator: function() { return []; },
+          previewWeakMap: function() { return []; },
+          previewWeakSet: function() { return []; }
         },
       };
     }
 
+
+
     setupV8();
     setupProcessICUVersions();