Implement CSSOM Smooth Scroll API

Source/platform/scroll/ScrollView.cpp

 /*
  * Copyright (C) 2006, 2007, 2008 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 261 matching lines @@
 
     if (scrollbarsSuppressed())
         return;
 
     if (isFrameView())
         m_pendingScrollDelta += scrollDelta;
     else
         scrollContents(scrollDelta);
 }
 
-void ScrollView::setScrollPosition(const IntPoint& scrollPoint)
+void ScrollView::setScrollPosition(const IntPoint& scrollPoint, ScrollBehavior scrollBehavior)
 {
     IntPoint newScrollPosition = adjustScrollPositionWithinRange(scrollPoint);
 
     if (newScrollPosition == scrollPosition())
         return;
 
-    updateScrollbars(IntSize(newScrollPosition.x(), newScrollPosition.y()));
+    if (scrollBehavior == ScrollBehaviorInstant)
+        updateScrollbars(IntSize(newScrollPosition.x(), newScrollPosition.y()));
+    else
+        ScrollableArea::programmaticallyScrollSmoothlyToOffset(newScrollPosition);
 }
 
 bool ScrollView::scroll(ScrollDirection direction, ScrollGranularity granularity)
 {
     ScrollDirection physicalDirection =
         toPhysicalDirection(direction, isVerticalDocument(), isFlippedDocument());
 
     return ScrollableArea::scroll(physicalDirection, granularity);
 }
 
@@ skipping 817 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(scrollOffset());
 }
 
 } // namespace WebCore