Take CSS Clip and contain: paint into account when computing visual rects.

third_party/WebKit/Source/core/paint/PaintLayer.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011, 2012 Apple Inc. All rights reserved.
  *
  * Portions are Copyright (C) 1998 Netscape Communications Corporation.
  *
  * Other contributors:
  *   Robert O'Callahan <roc+@cs.cmu.edu>
  *   David Baron <dbaron@fas.harvard.edu>
  *   Christian Biesinger <cbiesinger@web.de>
  *   Randall Jesup <rjesup@wgate.com>
@@ skipping 2396 matching lines @@
     if (m_stackingNode->zOrderListsDirty())
         return false;
 
     // FIXME: We currently only check the immediate layoutObject,
     // which will miss many cases.
     if (layoutObject()->backgroundIsKnownToBeOpaqueInRect(localRect))
         return true;
 
     // We can't consult child layers if we clip, since they might cover
     // parts of the rect that are clipped out.
-    if (layoutObject()->hasOverflowClip() || layoutObject()->style()->containsPaint())
+    if (layoutObject()->hasClipRelatedProperty())
         return false;
 
     return childBackgroundIsKnownToBeOpaqueInRect(localRect);
 }
 
 bool PaintLayer::childBackgroundIsKnownToBeOpaqueInRect(const LayoutRect& localRect) const
 {
     PaintLayerStackingNodeReverseIterator revertseIterator(*m_stackingNode, PositiveZOrderChildren | NormalFlowChildren | NegativeZOrderChildren);
     while (PaintLayerStackingNode* child = revertseIterator.next()) {
         const PaintLayer* childLayer = child->layer();
@@ skipping 496 matching lines @@
 
 void showLayerTree(const blink::LayoutObject* layoutObject)
 {
     if (!layoutObject) {
         fprintf(stderr, "Cannot showLayerTree. Root is (nil)\n");
         return;
     }
     showLayerTree(layoutObject->enclosingLayer());
 }
 #endif