Add ScrollDirectionPhysical enum in Scroll types.

Source/core/frame/RootFrameViewport.cpp

Index: Source/core/frame/RootFrameViewport.cpp
diff --git a/Source/core/frame/RootFrameViewport.cpp b/Source/core/frame/RootFrameViewport.cpp
index e4bb2ae60eb5777fe8a20f3f53ea339fb35d7cd0..e2dea23147c9d10a6b7a77eb7369492215801485 100644
--- a/Source/core/frame/RootFrameViewport.cpp
+++ b/Source/core/frame/RootFrameViewport.cpp
@@ -276,10 +276,8 @@ GraphicsLayer* RootFrameViewport::layerForVerticalScrollbar() const
     return layoutViewport().layerForVerticalScrollbar();
 }
 
-bool RootFrameViewport::scroll(ScrollDirection direction, ScrollGranularity granularity, float delta)
+bool RootFrameViewport::scroll(ScrollDirectionPhysical direction, ScrollGranularity granularity, float delta)
 {
-    ASSERT(!isLogical(direction));
-
     updateScrollAnimator();
 
     ScrollbarOrientation orientation;