Add |WebTextDirection toWebTextDirection(TextDirection)|.

public/web/WebTextDirection.h

 /*
  * Copyright (C) 2009 Google 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.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 13 matching lines @@
  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #ifndef WebTextDirection_h
 #define WebTextDirection_h
 
+#if BLINK_IMPLEMENTATION
+#include "platform/text/TextDirection.h"
+#endif
+
 namespace blink {
 
 // Represents text directions (or writing directions) of a DOM node.
 enum WebTextDirection {
     WebTextDirectionDefault,  // Natural writing direction ("inherit")
     WebTextDirectionLeftToRight,
     WebTextDirectionRightToLeft,
     WebTextDirectionLast = WebTextDirectionRightToLeft
 };
 
+#if BLINK_IMPLEMENTATION
+inline WebTextDirection toWebTextDirection(TextDirection direction)
+{
+    switch (direction) {
+    case LTR:
+        return WebTextDirectionLeftToRight;
+    case RTL:
+        return WebTextDirectionRightToLeft;
+    }
+    ASSERT_NOT_REACHED();
+    return WebTextDirectionDefault;
+}
+#endif
+
 } // namespace blink
 
 #endif