From 290eea38cffdb64a33bdb3cfc0d66c6e2233ed28 Mon Sep 17 00:00:00 2001
From: wolfbeast <mcwerewolf@gmail.com>
Date: Fri, 15 Jun 2018 14:03:56 +0200
Subject: [PATCH] Add a nullcheck in DOMProxyHandler::EnsureExpandoObject jic.

---
 dom/bindings/DOMJSProxyHandler.cpp | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/dom/bindings/DOMJSProxyHandler.cpp b/dom/bindings/DOMJSProxyHandler.cpp
index 65e540bc1d..23f0abd883 100644
--- a/dom/bindings/DOMJSProxyHandler.cpp
+++ b/dom/bindings/DOMJSProxyHandler.cpp
@@ -166,6 +166,10 @@ DOMProxyHandler::EnsureExpandoObject(JSContext* cx, JS::Handle<JSObject*> obj)
   nsISupports* native = UnwrapDOMObject<nsISupports>(obj);
   nsWrapperCache* cache;
   CallQueryInterface(native, &cache);
+  if (!cache) {
+    return expando;
+  }
+  
   if (expandoAndGeneration) {
     cache->PreserveWrapper(native);
     expandoAndGeneration->expando.setObject(*expando);