From 1f2c35311b1d994c04ead7b2c58822b57abb3ed9 Mon Sep 17 00:00:00 2001
From: Botond Ballo <botond@mozilla.com>
Date: Wed, 16 Nov 2016 15:59:24 -0500
Subject: [PATCH] Bug 1315854 - Account for rounding error when checking if
 certain transforms are the identity in
 AsyncCompositionManager::AlignFixedAndStickyLayers(). r=mstange

MozReview-Commit-ID: 4xxuqWHedeS

--HG--
extra : rebase_source : ee81a68b7e084896333cb0a9ac97a83e3c0f0388
---
 gfx/layers/composite/AsyncCompositionManager.cpp | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/gfx/layers/composite/AsyncCompositionManager.cpp b/gfx/layers/composite/AsyncCompositionManager.cpp
index 948ee4874cd7..69eafcecae70 100644
--- a/gfx/layers/composite/AsyncCompositionManager.cpp
+++ b/gfx/layers/composite/AsyncCompositionManager.cpp
@@ -478,6 +478,7 @@ AsyncCompositionManager::AlignFixedAndStickyLayers(Layer* aTransformedSubtreeRoo
     AccumulateLayerTransforms(layer->GetParent(), aTransformedSubtreeRoot,
                               ancestorTransform);
   }
+  ancestorTransform.NudgeToIntegersFixedEpsilon();
   MOZ_ASSERT(ancestorTransform.IsIdentity());
 #endif
 
@@ -488,6 +489,7 @@ AsyncCompositionManager::AlignFixedAndStickyLayers(Layer* aTransformedSubtreeRoo
 #ifdef DEBUG
   Matrix4x4 localTransform;
   GetBaseTransform(layer, &localTransform);
+  localTransform.NudgeToIntegersFixedEpsilon();
   MOZ_ASSERT(localTransform.IsIdentity());
 #endif