Implement CSSOM smooth scroll for Elements

Source/core/rendering/RenderBox.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2003, 2006, 2007 Apple 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.
  *
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Library General Public License for more details.
  *
  * You should have received a copy of the GNU Library General Public License
  * along with this library; see the file COPYING.LIB.  If not, write to
  * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  * Boston, MA 02110-1301, USA.
  *
  */
 
 #ifndef RenderBox_h
 #define RenderBox_h
 
 #include "core/rendering/RenderBoxModelObject.h"
 #include "core/rendering/RenderOverflow.h"
 #include "core/rendering/shapes/ShapeOutsideInfo.h"
 #include "platform/scroll/ScrollTypes.h"
+#include "platform/scroll/ScrollableArea.h"
 
 namespace blink {
 
 struct PaintInfo;
 
 enum SizeType { MainOrPreferredSize, MinSize, MaxSize };
 enum AvailableLogicalHeightType { ExcludeMarginBorderPadding, IncludeMarginBorderPadding };
 enum OverlayScrollbarSizeRelevancy { IgnoreOverlayScrollbarSize, IncludeOverlayScrollbarSize };
 enum MarginDirection { BlockDirection, InlineDirection };
 
@@ skipping 217 matching lines @@
     // scrolling).
     virtual LayoutUnit scrollLeft() const;
     virtual LayoutUnit scrollTop() const;
     virtual LayoutUnit scrollWidth() const;
     virtual LayoutUnit scrollHeight() const;
     int pixelSnappedScrollWidth() const;
     int pixelSnappedScrollHeight() const;
     virtual void setScrollLeft(LayoutUnit);
     virtual void setScrollTop(LayoutUnit);
 
-    void scrollToOffset(const DoubleSize&);
+    void scrollToOffset(const DoubleSize&, ScrollBehavior = ScrollBehaviorInstant);
     void scrollByRecursively(const DoubleSize& delta, ScrollOffsetClamping = ScrollOffsetUnclamped);
     void scrollRectToVisible(const LayoutRect&, const ScrollAlignment& alignX, const ScrollAlignment& alignY);
 
     virtual LayoutBoxExtent marginBox() const override { return m_marginBox; }
     virtual LayoutUnit marginTop() const override { return m_marginBox.top(); }
     virtual LayoutUnit marginBottom() const override { return m_marginBox.bottom(); }
     virtual LayoutUnit marginLeft() const override { return m_marginBox.left(); }
     virtual LayoutUnit marginRight() const override { return m_marginBox.right(); }
     void setMarginTop(LayoutUnit margin) { m_marginBox.setTop(margin); }
     void setMarginBottom(LayoutUnit margin) { m_marginBox.setBottom(margin); }
@@ skipping 560 matching lines @@
         if (UNLIKELY(inlineBoxWrapper() != 0))
             deleteLineBoxWrapper();
     }
 
     ensureRareData().m_inlineBoxWrapper = boxWrapper;
 }
 
 } // namespace blink
 
 #endif // RenderBox_h