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

Source/node_modules/core-js/modules/es6.object.prevent-extensions.js

@@ -0,0 +1,9 @@
+// 19.1.2.15 Object.preventExtensions(O)
+var isObject = require('./_is-object');
+var meta = require('./_meta').onFreeze;
+
+require('./_object-sap')('preventExtensions', function ($preventExtensions) {
+  return function preventExtensions(it) {
+    return $preventExtensions && isObject(it) ? $preventExtensions(meta(it)) : it;
+  };
+});