From 5102cafa8e154cb488f9a4b1563d27c97f41e1ae Mon Sep 17 00:00:00 2001
From: Matt Woodrow <mwoodrow@mozilla.com>
Date: Wed, 25 Jul 2012 09:39:01 +1200
Subject: [PATCH] Bug 770096 - Prevent crashes when encountering an empty
 ThebesLayer. r=roc

---
 layout/base/FrameLayerBuilder.cpp | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/layout/base/FrameLayerBuilder.cpp b/layout/base/FrameLayerBuilder.cpp
index 21b02b7d65d..e0c42b515c7 100644
--- a/layout/base/FrameLayerBuilder.cpp
+++ b/layout/base/FrameLayerBuilder.cpp
@@ -2630,6 +2630,10 @@ FrameLayerBuilder::DrawThebesLayer(ThebesLayer* aLayer,
     // so 'entry' could become invalid.
   }
 
+  if (!containerLayerFrame) {
+    return;
+  }
+
   ThebesDisplayItemLayerUserData* userData =
     static_cast<ThebesDisplayItemLayerUserData*>
       (aLayer->GetUserData(&gThebesDisplayItemLayerUserData));