From c5de81d0481b030774b4be29ef8bc69f98c9887e Mon Sep 17 00:00:00 2001
From: Daniel Freedman <dfreedm@google.com>
Date: Mon, 4 Nov 2013 17:33:17 -0800
Subject: [PATCH] Prevent accidentally overriding preventDefault with undefined

---
 src/dispatcher.js | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/dispatcher.js b/src/dispatcher.js
index 04da312a..5a4deba7 100644
--- a/src/dispatcher.js
+++ b/src/dispatcher.js
@@ -223,7 +223,9 @@
         inEvent.relatedTarget = null;
       }
       var e = new PointerEvent(inType, inEvent);
-      e.preventDefault = inEvent.preventDefault;
+      if (inEvent.preventDefault) {
+        e.preventDefault = inEvent.preventDefault;
+      }
       this.targets.set(e, this.targets.get(inEvent) || inEvent.target);
       return e;
     },