Add the text direction to the WebScrollbar interface.

Source/core/platform/ScrollableArea.h

 /*
  * Copyright (C) 2008, 2011 Apple Inc. All Rights Reserved.
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  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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 #ifndef ScrollableArea_h
 #define ScrollableArea_h
 
 #include "core/platform/Scrollbar.h"
+#include "core/platform/text/TextDirection.h"
 #include "wtf/Vector.h"
 
 namespace WebCore {
 
 class FloatPoint;
 class GraphicsContext;
 class GraphicsLayer;
 class PlatformGestureEvent;
 class PlatformWheelEvent;
 class ScrollAnimator;
@@ skipping 139 matching lines @@
     virtual void updateNeedsCompositedScrolling() { }
 
     virtual bool userInputScrollable(ScrollbarOrientation) const = 0;
 
     // Convenience functions
     int scrollPosition(ScrollbarOrientation orientation) { return orientation == HorizontalScrollbar ? scrollPosition().x() : scrollPosition().y(); }
     int minimumScrollPosition(ScrollbarOrientation orientation) { return orientation == HorizontalScrollbar ? minimumScrollPosition().x() : minimumScrollPosition().y(); }
     int maximumScrollPosition(ScrollbarOrientation orientation) { return orientation == HorizontalScrollbar ? maximumScrollPosition().x() : maximumScrollPosition().y(); }
     int clampScrollPosition(ScrollbarOrientation orientation, int pos)  { return std::max(std::min(pos, maximumScrollPosition(orientation)), minimumScrollPosition(orientation)); }
 
+    TextDirection textDirection() const;
+
 protected:
     ScrollableArea();
     virtual ~ScrollableArea();
 
     void setScrollOrigin(const IntPoint&);
     void resetScrollOriginChanged() { m_scrollOriginChanged = false; }
 
     virtual void invalidateScrollbarRect(Scrollbar*, const IntRect&) = 0;
     virtual void invalidateScrollCornerRect(const IntRect&) = 0;
 
@@ skipping 47 matching lines @@
     // vertical-lr / ltr            NO                      NO
     // vertical-lr / rtl            NO                      YES
     // vertical-rl / ltr            YES                     NO
     // vertical-rl / rtl            YES                     YES
     IntPoint m_scrollOrigin;
 };
 
 } // namespace WebCore
 
 #endif // ScrollableArea_h