From 377212290fd6f12cfbaa4f279ad5a861efb7c545 Mon Sep 17 00:00:00 2001
From: Sebastian McKenzie <sebmck@gmail.com>
Date: Fri, 23 Jan 2015 00:19:30 +1100
Subject: [PATCH] `6to5/polyfill` can now only be required **once**

---
 lib/6to5/polyfill.js | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/lib/6to5/polyfill.js b/lib/6to5/polyfill.js
index 248d028a58..f9a0420916 100644
--- a/lib/6to5/polyfill.js
+++ b/lib/6to5/polyfill.js
@@ -1,4 +1,9 @@
 "use strict";
 
+if (global._6to5Polyfill) {
+  throw new Error("only one instance of 6to5/polyfill is allowed");
+}
+global._6to5Polyfill = true;
+
 require("core-js/shim");
 require("regenerator-6to5/runtime");