First support for md extensions; Package all needed dependencies in the repo

Source/node_modules/core-js/modules/es7.object.entries.js

@@ -0,0 +1,9 @@
+// https://github.com/tc39/proposal-object-values-entries
+var $export = require('./_export');
+var $entries = require('./_object-to-array')(true);
+
+$export($export.S, 'Object', {
+  entries: function entries(it) {
+    return $entries(it);
+  }
+});