Add the text direction to the WebScrollbar interface.

Source/core/platform/ScrollableArea.cpp

 /*
  * Copyright (c) 2010, Google Inc. All rights reserved.
  * Copyright (C) 2008, 2011 Apple Inc. All Rights Reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
@@ skipping 384 matching lines @@
                    scrollPosition().y(),
                    std::max(0, visibleWidth() + verticalScrollbarWidth),
                    std::max(0, visibleHeight() + horizontalScrollbarHeight));
 }
 
 IntPoint ScrollableArea::clampScrollPosition(const IntPoint& scrollPosition) const
 {
     return scrollPosition.shrunkTo(maximumScrollPosition()).expandedTo(minimumScrollPosition());
 }
 
+TextDirection ScrollableArea::textDirection() const
+{
+    return !m_scrollOrigin.x() ? LTR : RTL;
+}
+
 int ScrollableArea::lineStep(ScrollbarOrientation) const
 {
     return pixelsPerLineStep();
 }
 
 int ScrollableArea::documentStep(ScrollbarOrientation orientation) const
 {
     return scrollSize(orientation);
 }
 
 float ScrollableArea::pixelStep(ScrollbarOrientation) const
 {
     return 1;
 }
 
 } // namespace WebCore