--- a/gfx/layers/composite/ContainerLayerComposite.cpp
+++ b/gfx/layers/composite/ContainerLayerComposite.cpp
@@ -42,48 +42,16 @@ HasOpaqueAncestorLayer(Layer* aLayer)
 {
   for (Layer* l = aLayer->GetParent(); l; l = l->GetParent()) {
     if (l->GetContentFlags() & Layer::CONTENT_OPAQUE)
       return true;
   }
   return false;
 }
 
-/**
- * Returns a rectangle of content painted opaquely by aLayer. Very consertative;
- * bails by returning an empty rect in any tricky situations.
- */
-static nsIntRect
-GetOpaqueRect(Layer* aLayer)
-{
-  nsIntRect result;
-  // Just bail if there's anything difficult to handle.
-  if (!aLayer->GetEffectiveTransform().IsIdentity() ||
-      aLayer->GetEffectiveOpacity() != 1.0f ||
-      aLayer->GetMaskLayer()) {
-    return result;
-  }
-  if (aLayer->GetContentFlags() & Layer::CONTENT_OPAQUE) {
-    result = aLayer->GetEffectiveVisibleRegion().GetLargestRectangle();
-  } else {
-    // Drill down into RefLayers because that's what we particularly care about;
-    // layer construction for aLayer will not have known about the opaqueness
-    // of any RefLayer subtrees.
-    RefLayer* refLayer = aLayer->AsRefLayer();
-    if (refLayer) {
-      result = GetOpaqueRect(refLayer->GetFirstChild());
-    }
-  }
-  const nsIntRect* clipRect = aLayer->GetEffectiveClipRect();
-  if (clipRect) {
-    result.IntersectRect(result, *clipRect);
-  }
-  return result;
-}
-
 template<class ContainerT> void
 ContainerRender(ContainerT* aContainer,
                 const nsIntPoint& aOffset,
                 LayerManagerComposite* aManager,
                 const nsIntRect& aClipRect)
 {
   /**
    * Setup our temporary surface for rendering the contents of this container.
@@ -170,33 +138,16 @@ ContainerRender(ContainerT* aContainer,
   for (uint32_t i = 0; i < children.Length(); i++) {
     LayerComposite* layerToRender = static_cast<LayerComposite*>(children.ElementAt(i)->ImplData());
 
     if (layerToRender->GetLayer()->GetEffectiveVisibleRegion().IsEmpty() &&
         !layerToRender->GetLayer()->AsContainerLayer()) {
       continue;
     }
 
-    if (i + 1 < children.Length() &&
-        layerToRender->GetLayer()->GetEffectiveTransform().IsIdentity()) {
-      LayerComposite* nextLayer = static_cast<LayerComposite*>(children.ElementAt(i + 1)->ImplData());
-      nsIntRect nextLayerOpaqueRect;
-      if (nextLayer && nextLayer->GetLayer()) {
-        nextLayerOpaqueRect = GetOpaqueRect(nextLayer->GetLayer());
-      }
-      if (!nextLayerOpaqueRect.IsEmpty()) {
-        nsIntRegion visibleRegion;
-        visibleRegion.Sub(layerToRender->GetShadowVisibleRegion(), nextLayerOpaqueRect);
-        layerToRender->SetShadowVisibleRegion(visibleRegion);
-        if (visibleRegion.IsEmpty()) {
-          continue;
-        }
-      }
-    }
-
     nsIntRect clipRect = layerToRender->GetLayer()->
         CalculateScissorRect(aClipRect, &aManager->GetWorldTransform());
     if (clipRect.IsEmpty()) {
       continue;
     }
 
     layerToRender->RenderLayer(childOffset, clipRect);
     // invariant: our GL context should be current here, I don't think we can