Use full mapLocalToAncestor machinery in ScrollingCoordinator.

third_party/WebKit/Source/core/paint/PaintLayerScrollableArea.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@gmail.com>
@@ skipping 580 matching lines @@
 }
 
 bool PaintLayerScrollableArea::scrollbarsCanBeActive() const {
   LayoutView* view = box().view();
   if (!view)
     return false;
   return view->frameView()->scrollbarsCanBeActive();
 }
 
 IntRect PaintLayerScrollableArea::scrollableAreaBoundingBox() const {
-  return box().absoluteBoundingBoxRect();
+  return box().absoluteBoundingBoxRect(TraverseDocumentBoundaries);
 }
 
 void PaintLayerScrollableArea::registerForAnimation() {
   if (LocalFrame* frame = box().frame()) {
     if (FrameView* frameView = frame->view())
       frameView->addAnimatingScrollableArea(this);
   }
 }
 
 void PaintLayerScrollableArea::deregisterForAnimation() {
@@ skipping 1504 matching lines @@
 
 void PaintLayerScrollableArea::DelayScrollOffsetClampScope::
     clampScrollableAreas() {
   for (auto& scrollableArea : *s_needsClamp)
     scrollableArea->clampScrollOffsetAfterOverflowChange();
   delete s_needsClamp;
   s_needsClamp = nullptr;
 }
 
 }  // namespace blink