From 25749a99333511c5857966b695b637dffc207522 Mon Sep 17 00:00:00 2001
From: Sebastian McKenzie <sebmck@gmail.com>
Date: Wed, 17 Jun 2015 16:53:08 +0100
Subject: [PATCH] clear properties to undefined in traverse.removeProperties

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

diff --git a/src/babel/traversal/index.js b/src/babel/traversal/index.js
index 6a8a59898c..58f854f0b9 100644
--- a/src/babel/traversal/index.js
+++ b/src/babel/traversal/index.js
@@ -51,7 +51,7 @@ const CLEAR_KEYS = [
 traverse.clearNode = function (node) {
   for (var i = 0; i < CLEAR_KEYS.length; i++) {
     let key = CLEAR_KEYS[i];
-    if (node[key] != null) node[key] = null;
+    if (node[key] != null) node[key] = undefined;
   }
 };