iframe updates its parent scrollable area set when its visibility change

Source/core/frame/FrameView.cpp

 /*
  * Copyright (C) 1998, 1999 Torben Weis <weis@kde.org>
  *                     1999 Lars Knoll <knoll@kde.org>
  *                     1999 Antti Koivisto <koivisto@kde.org>
  *                     2000 Dirk Mueller <mueller@kde.org>
  * Copyright (C) 2004, 2005, 2006, 2007, 2008 Apple Inc. All rights reserved.
  *           (C) 2006 Graham Dennis (graham.dennis@gmail.com)
  *           (C) 2006 Alexey Proskuryakov (ap@nypop.com)
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
@@ skipping 3940 matching lines @@
         return;
 
     for (const auto& child : m_children)
         child->setParentVisible(visible);
 }
 
 void FrameView::show()
 {
     if (!isSelfVisible()) {
         setSelfVisible(true);
+        updateScrollableAreaSet();
         if (isParentVisible()) {
             for (const auto& child : m_children)
                 child->setParentVisible(true);
         }
     }
 
     Widget::show();
 }
 
 void FrameView::hide()
 {
     if (isSelfVisible()) {
         if (isParentVisible()) {
             for (const auto& child : m_children)
                 child->setParentVisible(false);
         }
         setSelfVisible(false);
+        updateScrollableAreaSet();
     }
 
     Widget::hide();
 }
 
 void FrameView::addPanScrollIcon(const IntPoint& iconPosition)
 {
     HostWindow* window = hostWindow();
     if (!window)
         return;
@@ skipping 17 matching lines @@
         return;
 
     ScrollableArea::setScrollOrigin(origin);
 
     // Update if the scroll origin changes, since our position will be different if the content size did not change.
     if (updatePositionAtAll && updatePositionSynchronously)
         updateScrollbars(scrollOffsetDouble());
 }
 
 } // namespace blink