Add the text direction to the WebScrollbar interface.

Source/core/platform/ScrollableArea.h

Index: Source/core/platform/ScrollableArea.h
diff --git a/Source/core/platform/ScrollableArea.h b/Source/core/platform/ScrollableArea.h
index 0f2bf5f8094f38c6d7b8d8465d7771228ac3e57a..ca6614586a02dc056d037acb0d3c53ea05823d72 100644
--- a/Source/core/platform/ScrollableArea.h
+++ b/Source/core/platform/ScrollableArea.h
@@ -27,6 +27,7 @@
 #define ScrollableArea_h
 
 #include "core/platform/Scrollbar.h"
+#include "core/platform/text/TextDirection.h"
 #include "wtf/Vector.h"
 
 namespace WebCore {
@@ -186,6 +187,8 @@ public:
     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();