Don't add subpixel accumulations for squashed layers when invalidating them.

Source/core/rendering/RenderLayerModelObject.cpp

Index: Source/core/rendering/RenderLayerModelObject.cpp
diff --git a/Source/core/rendering/RenderLayerModelObject.cpp b/Source/core/rendering/RenderLayerModelObject.cpp
index 8beeaee4297dfce2b3081332979a6358d719322c..c3ab9d2d83cbe3e67cd9c96ac261721016f128c1 100644
--- a/Source/core/rendering/RenderLayerModelObject.cpp
+++ b/Source/core/rendering/RenderLayerModelObject.cpp
@@ -201,9 +201,10 @@ void RenderLayerModelObject::setBackingNeedsPaintInvalidationInRect(const Layout
     // FIXME: generalize accessors to backing GraphicsLayers so that this code is squashing-agnostic.
     if (layer()->groupedMapping()) {
         LayoutRect paintInvalidationRect = r;
-        paintInvalidationRect.move(layer()->subpixelAccumulation());
-        if (GraphicsLayer* squashingLayer = layer()->groupedMapping()->squashingLayer())
+        if (GraphicsLayer* squashingLayer = layer()->groupedMapping()->squashingLayer()) {
+            // Note: the subpixel accumulation of layer() does not need to be added here. It is already taken into account.
             squashingLayer->setNeedsDisplayInRect(pixelSnappedIntRect(paintInvalidationRect), invalidationReason);
+        }
     } else {
         layer()->compositedLayerMapping()->setContentsNeedDisplayInRect(r, invalidationReason);
     }