From 1aa112156375eb1189e89f6637b9b2b2c9124e0e Mon Sep 17 00:00:00 2001
From: Jamie Birch <14055146+shirakaba@users.noreply.github.com>
Date: Tue, 13 Mar 2018 16:11:24 +0000
Subject: [PATCH] polyfill if Promise.prototype.finally() is undefined.

---
 lib/es6-promise/polyfill.js | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/lib/es6-promise/polyfill.js b/lib/es6-promise/polyfill.js
index 30db73c..f4ffd8d 100644
--- a/lib/es6-promise/polyfill.js
+++ b/lib/es6-promise/polyfill.js
@@ -27,7 +27,9 @@ export default function polyfill() {
     }
 
     if (promiseToString === '[object Promise]' && !P.cast){
-      return;
+      if (typeof P.prototype.finally !== "undefined"){
+        return;
+      }
     }
   }