Add ScrollDirectionPhysical enum in Scroll types.

Source/core/layout/LayoutBox.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2005 Allan Sandfeld Jensen (kde@carewolf.com)
  *           (C) 2005, 2006 Samuel Weinig (sam.weinig@gmail.com)
  * Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2013 Adobe Systems Incorporated. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
@@ skipping 693 matching lines @@
     }
 
     if (!isHorizontalWritingMode() && style()->overflowX() == OSCROLL) {
         ASSERT(layer()->scrollableArea() && layer()->scrollableArea()->hasHorizontalScrollbar());
         return horizontalScrollbarHeight();
     }
 
     return 0;
 }
 
-bool LayoutBox::scroll(ScrollDirection direction, ScrollGranularity granularity, float delta)
+bool LayoutBox::scroll(ScrollDirectionPhysical direction, ScrollGranularity granularity, float delta)
 {
     // Presumably the same issue as in setScrollTop. See crbug.com/343132.
     DisableCompositingQueryAsserts disabler;
 
-    // Logical scroll is a higher level concept, all directions by here must be physical
-    ASSERT(!isLogical(direction));
-
     if (!layer() || !layer()->scrollableArea())
         return false;
 
     return layer()->scrollableArea()->scroll(direction, granularity, delta);
 }
 
 bool LayoutBox::canBeScrolledAndHasScrollableArea() const
 {
     return canBeProgramaticallyScrolled() && (pixelSnappedScrollHeight() != pixelSnappedClientHeight() || pixelSnappedScrollWidth() != pixelSnappedClientWidth());
 }
@@ skipping 4077 matching lines @@
 bool LayoutBox::canRenderBorderImage() const
 {
     if (!style()->hasBorder())
         return false;
 
     StyleImage* borderImage = style()->borderImage().image();
     return borderImage && borderImage->canRender(*this, style()->effectiveZoom()) && borderImage->isLoaded();
 }
 
 } // namespace blink