Correct the squashing origin w.r.t. the transformed ancestor to take into account rounding to integ…

Source/core/rendering/compositing/CompositedLayerMapping.cpp

Index: Source/core/rendering/compositing/CompositedLayerMapping.cpp
diff --git a/Source/core/rendering/compositing/CompositedLayerMapping.cpp b/Source/core/rendering/compositing/CompositedLayerMapping.cpp
index d81a0afa9ac3ba1656b6ecabf7928dd5cbf350ac..383f83a18db464921fdd2105fa80f820b37336b3 100644
--- a/Source/core/rendering/compositing/CompositedLayerMapping.cpp
+++ b/Source/core/rendering/compositing/CompositedLayerMapping.cpp
@@ -551,9 +551,6 @@ void CompositedLayerMapping::updateSquashingLayerGeometry(const LayoutPoint& off
         totalSquashBounds.unite(squashedBounds);
     }
 
-    *offsetFromTransformedAncestor = referenceOffsetFromTransformedAncestor;
-    offsetFromTransformedAncestor->moveBy(totalSquashBounds.location());
-
     // The totalSquashBounds is positioned with respect to referenceLayer of this CompositedLayerMapping.
     // But the squashingLayer needs to be positioned with respect to the ancestor CompositedLayerMapping.
     // The conversion between referenceLayer and the ancestor CLM is already computed as
@@ -566,6 +563,9 @@ void CompositedLayerMapping::updateSquashingLayerGeometry(const LayoutPoint& off
     squashingLayer->setPosition(squashLayerBounds.location());
     squashingLayer->setSize(squashLayerBounds.size());
 
+    *offsetFromTransformedAncestor = referenceOffsetFromTransformedAncestor;
+    offsetFromTransformedAncestor->move(squashLayerOriginInOwningLayerSpace);
+
     // Now that the squashing bounds are known, we can convert the RenderLayer painting offsets
     // from CLM owning layer space to the squashing layer space.
     //