Remove Widget's dependency upon its own inheritor aka ScrollView. This was nasty from an OO design…

Source/core/rendering/RenderWidget.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2000 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2004, 2006, 2009, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2013 Google Inc. 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
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
@@ skipping 42 matching lines @@
 
 RenderWidget::UpdateSuspendScope::~UpdateSuspendScope()
 {
     ASSERT(s_updateSuspendCount > 0);
     if (s_updateSuspendCount == 1) {
         WidgetToParentMap map;
         widgetNewParentMap().swap(map);
         WidgetToParentMap::iterator end = map.end();
         for (WidgetToParentMap::iterator it = map.begin(); it != end; ++it) {
             Widget* child = it->key.get();
-            ScrollView* currentParent = child->parent();
+            ScrollView* currentParent = toScrollView(child->parent());
             FrameView* newParent = it->value;
             if (newParent != currentParent) {
                 if (currentParent)
                     currentParent->removeChild(child);
                 if (newParent)
                     newParent->addChild(child);
             }
         }
     }
     --s_updateSuspendCount;
 }
 
 static void moveWidgetToParentSoon(Widget* child, FrameView* parent)
 {
     if (!s_updateSuspendCount) {
         if (parent)
             parent->addChild(child);
         else
-            child->removeFromParent();
+            toScrollView(child->parent())->removeChild(child);
         return;
     }
     widgetNewParentMap().set(child, parent);
 }
 
 RenderWidget::RenderWidget(Element* element)
     : RenderReplaced(element)
     , m_widget(0)
     , m_frameView(element->document().view())
     // Reference counting is used to prevent the widget from being
@@ skipping 280 matching lines @@
 CursorDirective RenderWidget::getCursor(const LayoutPoint& point, Cursor& cursor) const
 {
     if (widget() && widget()->isPluginView()) {
         // A plug-in is responsible for setting the cursor when the pointer is over it.
         return DoNotSetCursor;
     }
     return RenderReplaced::getCursor(point, cursor);
 }
 
 } // namespace WebCore