From f72e7f26442da8e3830ea85a5359c76bcfc19375 Mon Sep 17 00:00:00 2001
From: Greg Palmer <greg@gpalmer.me>
Date: Fri, 12 Aug 2016 09:11:09 -0700
Subject: [PATCH] Avoid "Member not found" error in IE

Explanation, discussion, and similar change as #7343

Addresses #7320
---
 src/renderers/shared/stack/event/SyntheticEvent.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/renderers/shared/stack/event/SyntheticEvent.js b/src/renderers/shared/stack/event/SyntheticEvent.js
index 1b01eebd91cfd..6c7d4fe16bc4e 100644
--- a/src/renderers/shared/stack/event/SyntheticEvent.js
+++ b/src/renderers/shared/stack/event/SyntheticEvent.js
@@ -121,7 +121,7 @@ Object.assign(SyntheticEvent.prototype, {
 
     if (event.preventDefault) {
       event.preventDefault();
-    } else {
+    } else if (typeof event.returnValue !== 'unknown') { // eslint-disable-line valid-typeof
       event.returnValue = false;
     }
     this.isDefaultPrevented = emptyFunction.thatReturnsTrue;