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 267 matching lines @@
     m_scrollOffset = newOffset;
 
     if (scrollbarsSuppressed())
         return;
 
     repaintFixedElementsAfterScrolling();
     scrollContents(scrollDelta);
     updateFixedElementsAfterScrolling();
 }
 
-void ScrollView::setScrollPosition(const IntPoint& scrollPoint)
+void ScrollView::setScrollPosition(const IntPoint& scrollPoint, ScrollBehavior behavior)
 {
     IntPoint newScrollPosition = adjustScrollPositionWithinRange(scrollPoint);
 
     if (newScrollPosition == scrollPosition())
         return;
 
-    updateScrollbars(IntSize(newScrollPosition.x(), newScrollPosition.y()));
+    if (behavior == 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 829 matching lines @@
 int ScrollView::pageStep(ScrollbarOrientation orientation) const
 {
     int length = (orientation == HorizontalScrollbar) ? visibleWidth() : visibleHeight();
     int minPageStep = static_cast<float>(length) * minFractionToStepWhenPaging();
     int pageStep = std::max(minPageStep, length - maxOverlapBetweenPages());
 
     return std::max(pageStep, 1);
 }
 
 } // namespace WebCore