From aaa28cd3d5e482c1c7f4989ecc23fcf5d4e5ff52 Mon Sep 17 00:00:00 2001
From: win7-7 <win7-7@users.noreply.github.com>
Date: Thu, 2 May 2019 16:47:23 +0300
Subject: [PATCH] patch to Bug 1363423

---
 layout/base/FrameLayerBuilder.cpp | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/layout/base/FrameLayerBuilder.cpp b/layout/base/FrameLayerBuilder.cpp
index 1832854398..b315c348ac 100644
--- a/layout/base/FrameLayerBuilder.cpp
+++ b/layout/base/FrameLayerBuilder.cpp
@@ -3648,6 +3648,10 @@ PaintedLayerData::AccumulateEventRegions(ContainerState* aState, nsDisplayLayerE
   if (alreadyHadRegions) {
     mDispatchToContentHitRegion.OrWith(CombinedTouchActionRegion());
   }
+  
+  // Avoid quadratic performance as a result of the region growing to include
+  // and arbitrarily large number of rects, which can happen on some pages.
+  mMaybeHitRegion.SimplifyOutward(8);
 
   // Calculate scaled versions of the bounds of mHitRegion and mMaybeHitRegion
   // for quick access in FindPaintedLayerFor().
@@ -6368,3 +6372,4 @@ ContainerState::CreateMaskLayer(Layer *aLayer,
 }
 
 } // namespace mozilla
+