So siehts ganz gut aus !

node_modules/core-js/modules/es7.reflect.has-own-metadata.js

@@ -0,0 +1,9 @@
+var metadata = require('./_metadata');
+var anObject = require('./_an-object');
+var ordinaryHasOwnMetadata = metadata.has;
+var toMetaKey = metadata.key;
+
+metadata.exp({ hasOwnMetadata: function hasOwnMetadata(metadataKey, target /* , targetKey */) {
+  return ordinaryHasOwnMetadata(metadataKey, anObject(target)
+    , arguments.length < 3 ? undefined : toMetaKey(arguments[2]));
+} });