From 804f5a843ceb2b8498f838f2a56a5f16e36fc381 Mon Sep 17 00:00:00 2001
From: Alexander Surkov <surkov.alexander@gmail.com>
Date: Mon, 28 Mar 2011 22:59:17 +0900
Subject: [PATCH] Bug 628603 - Crash in nsDocAccessible::CacheChildrenInSubtree
 [@ nsAccessNode::IsContent() ], r=davidb, a=blocking2.x+

---
 accessible/src/base/nsDocAccessible.cpp | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/accessible/src/base/nsDocAccessible.cpp b/accessible/src/base/nsDocAccessible.cpp
index 4f2909bec93..91774bfa635 100644
--- a/accessible/src/base/nsDocAccessible.cpp
+++ b/accessible/src/base/nsDocAccessible.cpp
@@ -1953,8 +1953,9 @@ nsDocAccessible::CacheChildrenInSubtree(nsAccessible* aRoot)
   PRUint32 count = aRoot->GetChildCount();
   for (PRUint32 idx = 0; idx < count; idx++)  {
     nsAccessible* child = aRoot->GetChildAt(idx);
+    NS_ASSERTION(child, "Illicit tree change while tree is created!");
     // Don't cross document boundaries.
-    if (child->IsContent())
+    if (child && child->IsContent())
       CacheChildrenInSubtree(child);
   }
 }