Add ScrollDirectionPhysical enum in Scroll types.

Source/platform/scroll/ScrollableArea.cpp

Index: Source/platform/scroll/ScrollableArea.cpp
diff --git a/Source/platform/scroll/ScrollableArea.cpp b/Source/platform/scroll/ScrollableArea.cpp
index 55dd4ae3522c2c79e10c19de48ef3112a0a4761d..301497c722017d5a8e2fba4bd0f6b43137328cc9 100644
--- a/Source/platform/scroll/ScrollableArea.cpp
+++ b/Source/platform/scroll/ScrollableArea.cpp
@@ -122,12 +122,10 @@ GraphicsLayer* ScrollableArea::layerForContainer() const
     return layerForScrolling() ? layerForScrolling()->parent() : 0;
 }
 
-bool ScrollableArea::scroll(ScrollDirection direction, ScrollGranularity granularity, float delta)
+bool ScrollableArea::scroll(ScrollDirectionPhysical direction, ScrollGranularity granularity, float delta)
 {
-    ASSERT(!isLogical(direction));
-
     ScrollbarOrientation orientation;
-    if (direction == ScrollUp || direction == ScrollDown)
+    if (direction == ScrollPhysicalUp || direction == ScrollPhysicalDown)
         orientation = VerticalScrollbar;
     else
         orientation = HorizontalScrollbar;
@@ -154,7 +152,7 @@ bool ScrollableArea::scroll(ScrollDirection direction, ScrollGranularity granula
         break;
     }
 
-    if (direction == ScrollUp || direction == ScrollLeft)
+    if (direction == ScrollPhysicalUp || direction == ScrollPhysicalLeft)
         delta = -delta;
 
     return scrollAnimator()->scroll(orientation, granularity, step, delta).didScroll;