DeprecatedPaintLayerStackingNode should walk DPL

Source/core/paint/DeprecatedPaintLayer.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 1348 matching lines @@
     } else if (m_reflectionInfo) {
         m_reflectionInfo->destroy();
         m_reflectionInfo = nullptr;
     }
 }
 
 void DeprecatedPaintLayer::updateStackingNode()
 {
     ASSERT(!m_stackingNode);
     if (requiresStackingNode())
-        m_stackingNode = adoptPtr(new DeprecatedPaintLayerStackingNode(*layoutObject()));
+        m_stackingNode = adoptPtr(new DeprecatedPaintLayerStackingNode(this));
+    else
+        m_stackingNode = nullptr;
 }
 
 void DeprecatedPaintLayer::updateScrollableArea()
 {
     ASSERT(!m_scrollableArea);
     if (requiresScrollableArea())
         m_scrollableArea = DeprecatedPaintLayerScrollableArea::create(*this);
 }
 
 bool DeprecatedPaintLayer::hasOverflowControls() const
@@ skipping 162 matching lines @@
 Node* DeprecatedPaintLayer::enclosingElement() const
 {
     for (LayoutObject* r = layoutObject(); r; r = r->parent()) {
         if (Node* e = r->node())
             return e;
     }
     ASSERT_NOT_REACHED();
     return 0;
 }
 
+bool DeprecatedPaintLayer::isInTopLayer() const
+{
+    Node* node = layoutObject()->node();
+    return node && node->isElementNode() && toElement(node)->isInTopLayer();
+}
+
 // Compute the z-offset of the point in the transformState.
 // This is effectively projecting a ray normal to the plane of ancestor, finding where that
 // ray intersects target, and computing the z delta between those two points.
 static double computeZOffset(const HitTestingTransformState& transformState)
 {
     // We got an affine transform, so no z-offset
     if (transformState.m_accumulatedTransform.isAffine())
         return 0;
 
     // Flatten the point into the target plane
@@ skipping 1153 matching lines @@
 
 void showLayerTree(const blink::LayoutObject* layoutObject)
 {
     if (!layoutObject) {
         fprintf(stderr, "Cannot showLayerTree. Root is (nil)\n");
         return;
     }
     showLayerTree(layoutObject->enclosingLayer());
 }
 #endif