Implement canvas2d direction attribute

Source/core/html/canvas/CanvasRenderingContext2D.h

Index: Source/core/html/canvas/CanvasRenderingContext2D.h
diff --git a/Source/core/html/canvas/CanvasRenderingContext2D.h b/Source/core/html/canvas/CanvasRenderingContext2D.h
index 6eba5f5b313772a10a5e9c24f1d7f6c3be305281..7dae8870e730a27d21b8275801311b2b842afdb8 100644
--- a/Source/core/html/canvas/CanvasRenderingContext2D.h
+++ b/Source/core/html/canvas/CanvasRenderingContext2D.h
@@ -211,6 +211,9 @@ public:
     String textBaseline() const;
     void setTextBaseline(const String&);
 
+    String direction() const;
+    void setDirection(const String&);
+
     void fillText(const String& text, float x, float y);
     void fillText(const String& text, float x, float y, float maxWidth);
     void strokeText(const String& text, float x, float y);
@@ -241,9 +244,15 @@ public:
     virtual void trace(Visitor*) OVERRIDE;
 
 private:
+    enum Direction {
+        DirectionInherit = -1,
+        DirectionRTL,
+        DirectionLTR
+    };
+
     class State FINAL : public CSSFontSelectorClient {
     public:
-        State();
+        explicit State(Direction = DirectionInherit);
         virtual ~State();
 
         State(const State&);
@@ -279,6 +288,7 @@ private:
         // Text state.
         TextAlign m_textAlign;
         TextBaseline m_textBaseline;
+        Direction m_direction;
 
         String m_unparsedFont;
         Font m_font;