The "children transform layer" needs an anchor point

Source/core/rendering/compositing/CompositedLayerMapping.cpp

 /*
  * Copyright (C) 2009, 2010, 2011 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 735 matching lines @@
         // Compute the anchor point, which is in the center of the renderer box unless transform-origin is set.
         FloatPoint3D anchor(
             relativeCompositingBounds.width() ? (layerBounds.x() - relativeCompositingBounds.x() + transformOrigin.x()) / relativeCompositingBounds.width()  : 0.5f,
             relativeCompositingBounds.height() ? (layerBounds.y() - relativeCompositingBounds.y() + transformOrigin.y()) / relativeCompositingBounds.height() : 0.5f,
             transformOrigin.z());
         m_graphicsLayer->setAnchorPoint(anchor);
     } else {
         m_graphicsLayer->setAnchorPoint(FloatPoint3D(0.5f, 0.5f, 0));
     }
 
+    if (GraphicsLayer* childrenTransformLayer = layerForChildrenTransform())
+        childrenTransformLayer->setAnchorPoint(m_graphicsLayer->anchorPoint());
+
     if (m_foregroundLayer) {
         FloatSize foregroundSize = contentsSize;
         IntSize foregroundOffset = m_graphicsLayer->offsetFromRenderer();
         if (hasClippingLayer()) {
             // If we have a clipping layer (which clips descendants), then the foreground layer is a child of it,
             // so that it gets correctly sorted with children. In that case, position relative to the clipping layer.
             foregroundSize = FloatSize(clippingBox.size());
             foregroundOffset = toIntSize(clippingBox.location());
         }
 
@@ skipping 1349 matching lines @@
     } else if (graphicsLayer == m_scrollingContentsLayer.get()) {
         name = "Scrolling Contents Layer";
     } else {
         ASSERT_NOT_REACHED();
     }
 
     return name;
 }
 
 } // namespace WebCore