Implement CSSOM Smooth Scroll API

Source/core/rendering/RenderBox.cpp

Index: Source/core/rendering/RenderBox.cpp
diff --git a/Source/core/rendering/RenderBox.cpp b/Source/core/rendering/RenderBox.cpp
index abf97e337275b9b818e57e6032ed1489f7674130..5afcacf1230b8c2c387bb1eb4d5a2cfd8b7405cc 100644
--- a/Source/core/rendering/RenderBox.cpp
+++ b/Source/core/rendering/RenderBox.cpp
@@ -487,16 +487,16 @@ int RenderBox::scrollTop() const
     return hasOverflowClip() ? layer()->scrollableArea()->scrollYOffset() : 0;
 }
 
-void RenderBox::setScrollLeft(int newLeft)
+void RenderBox::setScrollLeft(int newLeft, ScrollBehavior scrollBehavior)
 {
     if (hasOverflowClip())
-        layer()->scrollableArea()->scrollToXOffset(newLeft, ScrollOffsetClamped);
+        layer()->scrollableArea()->scrollToXOffset(newLeft, ScrollOffsetClamped, scrollBehavior);
 }
 
-void RenderBox::setScrollTop(int newTop)
+void RenderBox::setScrollTop(int newTop, ScrollBehavior scrollBehavior)
 {
     if (hasOverflowClip())
-        layer()->scrollableArea()->scrollToYOffset(newTop, ScrollOffsetClamped);
+        layer()->scrollableArea()->scrollToYOffset(newTop, ScrollOffsetClamped, scrollBehavior);
 }
 
 void RenderBox::scrollToOffset(const IntSize& offset)