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..5bca94802ee9ff358cfe0a60643b2af6f77808aa 100644
--- a/Source/core/rendering/RenderLayerModelObject.cpp
+++ b/Source/core/rendering/RenderLayerModelObject.cpp
@@ -201,9 +201,11 @@ 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())
-            squashingLayer->setNeedsDisplayInRect(pixelSnappedIntRect(paintInvalidationRect), invalidationReason);
+        if (GraphicsLayer* squashingLayer = layer()->groupedMapping()->squashingLayer()) {
+            // Note: the subpixel accumulation of layer() does not need

[leviw_travelin_and_unemployed, 2014/10/14 21:49:09]

Nit: Did you not finish writing this comment?

[chrishtr, 2014/10/14 21:54:32]

Done

+            IntRect snappedRect = pixelSnappedIntRect(paintInvalidationRect);

[leviw_travelin_and_unemployed, 2014/10/14 21:49:09]

Why bother with adding the local variable?

[chrishtr, 2014/10/14 21:54:32]

Done.

+            squashingLayer->setNeedsDisplayInRect(snappedRect, invalidationReason);
+        }
     } else {
         layer()->compositedLayerMapping()->setContentsNeedDisplayInRect(r, invalidationReason);
     }