Add |WebTextDirection toWebTextDirection(TextDirection)|.

Source/web/WebViewImpl.cpp

Index: Source/web/WebViewImpl.cpp
diff --git a/Source/web/WebViewImpl.cpp b/Source/web/WebViewImpl.cpp
index 1b3aa3ed31d52c0d60fd5fcf93ad07499d51043f..f8dc7383f629551522a827034a4c4b8fc571156e 100644
--- a/Source/web/WebViewImpl.cpp
+++ b/Source/web/WebViewImpl.cpp
@@ -2430,8 +2430,8 @@ bool WebViewImpl::selectionTextDirection(WebTextDirection& start, WebTextDirecti
     FrameSelection& selection = frame->selection();
     if (!selection.toNormalizedRange())
         return false;
-    start = selection.start().primaryDirection() == RTL ? WebTextDirectionRightToLeft : WebTextDirectionLeftToRight;
-    end = selection.end().primaryDirection() == RTL ? WebTextDirectionRightToLeft : WebTextDirectionLeftToRight;
+    start = toWebTextDirection(selection.start().primaryDirection());
+    end = toWebTextDirection(selection.end().primaryDirection());
     return true;
 }