From 7572d5deb5eeb1f64c0bfb12cd5109b989f1009c Mon Sep 17 00:00:00 2001
From: Matt Woodrow <mwoodrow@mozilla.com>
Date: Fri, 23 Oct 2015 11:22:54 +1300
Subject: [PATCH] Bug 1216851 - Don't include event regions when deciding if we
 can flatten opacity. r=roc

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

diff --git a/layout/base/nsDisplayList.cpp b/layout/base/nsDisplayList.cpp
index 441074446a5..f9eb12926a8 100644
--- a/layout/base/nsDisplayList.cpp
+++ b/layout/base/nsDisplayList.cpp
@@ -3962,6 +3962,10 @@ nsDisplayOpacity::ShouldFlattenAway(nsDisplayListBuilder* aBuilder)
   bool snap;
   uint32_t numChildren = 0;
   for (; numChildren < ArrayLength(children) && child; numChildren++, child = child->GetAbove()) {
+    if (child->GetType() == nsDisplayItem::TYPE_LAYER_EVENT_REGIONS) {
+      numChildren--;
+      continue;
+    }
     if (!child->CanApplyOpacity()) {
       return false;
     }