Fix incorrect use of coords conversion for sticky elements

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>
@@ skipping 1470 matching lines @@
   }
 
   if (!containing_layer)
     return nullptr;
 
   location += layer->Location();
   return containing_layer;
 }
 
 void PaintLayer::ConvertToLayerCoords(const PaintLayer* ancestor_layer,
-                                      LayoutPoint& location) const {
+                                      LayoutPoint& location,
+                                      bool* is_descendant) const {
   if (ancestor_layer == this)
     return;
 
   const PaintLayer* curr_layer = this;
   while (curr_layer && curr_layer != ancestor_layer)
     curr_layer =
         AccumulateOffsetTowardsAncestor(curr_layer, ancestor_layer, location);
+
+  if (is_descendant)
+    *is_descendant = curr_layer == ancestor_layer;
 }
 
 void PaintLayer::ConvertToLayerCoords(const PaintLayer* ancestor_layer,
                                       LayoutRect& rect) const {
   LayoutPoint delta;
   ConvertToLayerCoords(ancestor_layer, delta);
   rect.MoveBy(delta);
 }
 
 LayoutPoint PaintLayer::VisualOffsetFromAncestor(
@@ skipping 1819 matching lines @@
 }
 
 void showLayerTree(const blink::LayoutObject* layoutObject) {
   if (!layoutObject) {
     LOG(INFO) << "Cannot showLayerTree. Root is (nil)";
     return;
   }
   showLayerTree(layoutObject->EnclosingLayer());
 }
 #endif