From cdcedaa853cbb198209ca96588f2601297cc39fa Mon Sep 17 00:00:00 2001
From: Thomas Grainger <tagrain@gmail.com>
Date: Tue, 9 May 2017 00:10:37 +0100
Subject: [PATCH 1/2] avoid Array.from and Reflect

---
 src/index.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/index.js b/src/index.js
index 5e34095..ed10dc4 100644
--- a/src/index.js
+++ b/src/index.js
@@ -9,7 +9,7 @@ const buildHelper = template(`
         function ExtendableBuiltin(){
             // Not passing "newTarget" because core-js would fall back to non-exotic
             // object creation.
-            var instance = Reflect.construct(cls, Array.from(arguments));
+            var instance = new (Function.prototype.bind.apply(cls, arguments))();
             Object.setPrototypeOf(instance, Object.getPrototypeOf(this));
             return instance;
         }

From aafe8fe115ff3c0ed491a59c2477d9092db3bab6 Mon Sep 17 00:00:00 2001
From: Thomas Grainger <tom@procensus.com>
Date: Tue, 9 May 2017 00:20:50 +0100
Subject: [PATCH 2/2] consistent use of get/setPrototypeOf polyfill

---
 src/index.js | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/src/index.js b/src/index.js
index ed10dc4..dc0e016 100644
--- a/src/index.js
+++ b/src/index.js
@@ -6,11 +6,17 @@ import template from 'babel-template';
  */
 const buildHelper = template(`
     function HELPER(cls){
+        var setPrototypeOf = Object.setPrototypeOf || (function setPrototypeOf(a, b) {
+            a.__proto__ = b;
+        });
+        var getPrototypeOf = Object.getPrototypeOf || (function getPrototypeOf(a)) {
+            return a.__proto__;
+        });
         function ExtendableBuiltin(){
             // Not passing "newTarget" because core-js would fall back to non-exotic
             // object creation.
             var instance = new (Function.prototype.bind.apply(cls, arguments))();
-            Object.setPrototypeOf(instance, Object.getPrototypeOf(this));
+            setPrototypeOf(instance, getPrototypeOf(this));
             return instance;
         }
         ExtendableBuiltin.prototype = Object.create(cls.prototype, {
@@ -21,12 +27,8 @@ const buildHelper = template(`
                 configurable: true,
             },
         });
-        if (Object.setPrototypeOf){
-            Object.setPrototypeOf(ExtendableBuiltin, cls);
-        } else {
-            ExtendableBuiltin.__proto__ = cls;
-        }
 
+        setPrototypeOf(ExtendableBuiltin, cls);
         return ExtendableBuiltin;
     }
 `);