Drag'n drop Autoscroll does not work properly on inner frames

Source/core/rendering/RenderBox.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2005 Allan Sandfeld Jensen (kde@carewolf.com)
  *           (C) 2005, 2006 Samuel Weinig (sam.weinig@gmail.com)
  * Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2013 Adobe Systems Incorporated. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
@@ skipping 751 matching lines @@
 // scrolling.
 IntSize RenderBox::calculateAutoscrollDirection(const IntPoint& windowPoint) const
 {
     if (!frame())
         return IntSize();
 
     FrameView* frameView = frame()->view();
     if (!frameView)
         return IntSize();
 
-    IntSize offset;
-    IntPoint point = frameView->windowToContents(windowPoint);
     IntRect box(absoluteBoundingBoxRect());
-    if (isRenderView())
-        box.moveBy(frameView->windowToContents(IntPoint()));
+    box.move(view()->frameView()->scrollOffset());
+    IntRect windowBox = view()->frameView()->contentsToWindow(box);
 
-    if (point.x() < box.x() + autoscrollBeltSize)
-        point.move(-autoscrollBeltSize, 0);
-    else if (point.x() > box.maxX() - autoscrollBeltSize)
-        point.move(autoscrollBeltSize, 0);
+    IntPoint windowAutoscrollPoint = windowPoint;
 
-    if (point.y() < box.y() + autoscrollBeltSize)
-        point.move(0, -autoscrollBeltSize);
-    else if (point.y() > box.maxY() - autoscrollBeltSize)
-        point.move(0, autoscrollBeltSize);
-    return frameView->contentsToWindow(point) - windowPoint;
+    if (windowAutoscrollPoint.x() < windowBox.x() + autoscrollBeltSize)
+        windowAutoscrollPoint.move(-autoscrollBeltSize, 0);
+    else if (windowAutoscrollPoint.x() > windowBox.maxX() - autoscrollBeltSize)
+        windowAutoscrollPoint.move(autoscrollBeltSize, 0);
+
+    if (windowAutoscrollPoint.y() < windowBox.y() + autoscrollBeltSize)
+        windowAutoscrollPoint.move(0, -autoscrollBeltSize);
+    else if (windowAutoscrollPoint.y() > windowBox.maxY() - autoscrollBeltSize)
+        windowAutoscrollPoint.move(0, autoscrollBeltSize);
+
+    return windowAutoscrollPoint - windowPoint;
 }
 
 RenderBox* RenderBox::findAutoscrollable(RenderObject* renderer)
 {
     while (renderer && !(renderer->isBox() && toRenderBox(renderer)->canAutoscroll())) {
         if (!renderer->parent() && renderer->node() == &renderer->document() && renderer->document().ownerElement())
             renderer = renderer->document().ownerElement()->renderer();
         else
             renderer = renderer->parent();
     }
@@ skipping 3912 matching lines @@
         return 0;
 
     if (!layoutState && !flowThreadContainingBlock())
         return 0;
 
     RenderBlock* containerBlock = containingBlock();
     return containerBlock->offsetFromLogicalTopOfFirstPage() + logicalTop();
 }
 
 } // namespace WebCore