So siehts ganz gut aus !

node_modules/core-js/modules/es7.reflect.get-own-metadata-keys.js

@@ -0,0 +1,8 @@
+var metadata = require('./_metadata');
+var anObject = require('./_an-object');
+var ordinaryOwnMetadataKeys = metadata.keys;
+var toMetaKey = metadata.key;
+
+metadata.exp({ getOwnMetadataKeys: function getOwnMetadataKeys(target /* , targetKey */) {
+  return ordinaryOwnMetadataKeys(anObject(target), arguments.length < 2 ? undefined : toMetaKey(arguments[1]));
+} });