Oilpan: fix build after r183816

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 2371 matching lines @@
         result = result.blend(htmlElement->renderer()->style()->visitedDependentColor(CSSPropertyBackgroundColor));
     if (bodyElement && bodyElement->renderer())
         result = result.blend(bodyElement->renderer()->style()->visitedDependentColor(CSSPropertyBackgroundColor));
 
     return result;
 }
 
 bool FrameView::hasCustomScrollbars() const
 {
     const ChildrenWidgetSet* viewChildren = children();
-    for (const auto& child : *viewChildren) {
+    for (const RefPtrWillBeMember<Widget>& child : *viewChildren) {
         Widget* widget = child.get();
         if (widget->isFrameView()) {
             if (toFrameView(widget)->hasCustomScrollbars())
                 return true;
         } else if (widget->isScrollbar()) {
-            Scrollbar* scrollbar = static_cast<Scrollbar*>(widget);
-            if (scrollbar->isCustomScrollbar())
+            if (toScrollbar(widget)->isCustomScrollbar())
                 return true;
         }
     }
 
     return false;
 }
 
 FrameView* FrameView::parentFrameView() const
 {
     if (!parent())
@@ skipping 1594 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