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

Source/core/rendering/RenderBox.cpp

Index: Source/core/rendering/RenderBox.cpp
diff --git a/Source/core/rendering/RenderBox.cpp b/Source/core/rendering/RenderBox.cpp
index 84e550a7798d4d4f302644e0ae06c575e692a200..a1144c0cdf0d6f3a8e658ec8d884d8b6b24532c4 100644
--- a/Source/core/rendering/RenderBox.cpp
+++ b/Source/core/rendering/RenderBox.cpp
@@ -769,22 +769,23 @@ IntSize RenderBox::calculateAutoscrollDirection(const IntPoint& windowPoint) con
     if (!frameView)
         return IntSize();
 
-    IntSize offset;
-    IntPoint point = frameView->windowToContents(windowPoint);
     IntRect box(absoluteBoundingBoxRect());
-    if (isRenderView())
-        box.moveBy(frameView->windowToContents(IntPoint()));
-
-    if (point.x() < box.x() + autoscrollBeltSize)
-        point.move(-autoscrollBeltSize, 0);
-    else if (point.x() > box.maxX() - autoscrollBeltSize)
-        point.move(autoscrollBeltSize, 0);
-
-    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;
+    box.move(view()->frameView()->scrollOffset());
+    IntRect windowBox = view()->frameView()->contentsToWindow(box);
+
+    IntPoint windowAutoscrollPoint = 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)