From 7394d7ef479c638d298fca98addd936c14c060da Mon Sep 17 00:00:00 2001
From: Matt Woodrow <mwoodrow@mozilla.com>
Date: Mon, 15 Apr 2013 18:55:29 +1200
Subject: [PATCH] Bug 857817 - Make AreLayerMarkedActive aware of preserve-3d
 transformed frames. r=roc

---
 layout/generic/nsFrame.cpp | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/layout/generic/nsFrame.cpp b/layout/generic/nsFrame.cpp
index a0c3655d8428..7e28cbd8cde1 100644
--- a/layout/generic/nsFrame.cpp
+++ b/layout/generic/nsFrame.cpp
@@ -4583,7 +4583,14 @@ nsIFrame::AreLayersMarkedActive(nsChangeHint aChangeHint)
 {
   LayerActivity* layerActivity =
     static_cast<LayerActivity*>(Properties().Get(LayerActivityProperty()));
-  return layerActivity && (layerActivity->mChangeHint & aChangeHint);
+  if (layerActivity && (layerActivity->mChangeHint & aChangeHint)) {
+    return true;
+  }
+  if (aChangeHint & nsChangeHint_UpdateTransformLayer &&
+      Preserves3D()) {
+    return GetParent()->AreLayersMarkedActive(nsChangeHint_UpdateTransformLayer);
+  }
+  return false;
 }
 
 /* static */ void