Add ScrollDirectionPhysical enum in Scroll types.

Source/core/frame/RootFrameViewport.cpp

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "config.h"
 #include "core/frame/RootFrameViewport.h"
 
 #include "core/frame/FrameView.h"
 #include "core/layout/ScrollAlignment.h"
 #include "platform/geometry/DoubleRect.h"
@@ skipping 258 matching lines @@
 GraphicsLayer* RootFrameViewport::layerForHorizontalScrollbar() const
 {
     return layoutViewport().layerForHorizontalScrollbar();
 }
 
 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;
 
     if (direction == ScrollUp || direction == ScrollDown)
         orientation = VerticalScrollbar;
     else
         orientation = HorizontalScrollbar;
 
     if (layoutViewport().userInputScrollable(orientation) && visualViewport().userInputScrollable(orientation))
         return ScrollableArea::scroll(direction, granularity, delta);
 
     if (visualViewport().userInputScrollable(orientation))
         return visualViewport().scroll(direction, granularity, delta);
 
     if (layoutViewport().userInputScrollable(orientation))
         return layoutViewport().scroll(direction, granularity, delta);
 
     return false;
 }
 
 } // namespace blink