Introduce enum class TextAffinity as replacement of enum EAffinity

Source/core/editing/commands/ApplyBlockElementCommand.cpp

Index: Source/core/editing/commands/ApplyBlockElementCommand.cpp
diff --git a/Source/core/editing/commands/ApplyBlockElementCommand.cpp b/Source/core/editing/commands/ApplyBlockElementCommand.cpp
index b20c9f8d09596a3440576552ac08c21251bc2836..fa4facd3c7b20e1fd22b0aa415450551ee1ce2bc 100644
--- a/Source/core/editing/commands/ApplyBlockElementCommand.cpp
+++ b/Source/core/editing/commands/ApplyBlockElementCommand.cpp
@@ -116,7 +116,7 @@ void ApplyBlockElementCommand::formatSelection(const VisiblePosition& startOfSel
         insertNodeAt(blockquote, start);
         RefPtrWillBeRawPtr<HTMLBRElement> placeholder = createBreakElement(document());
         appendNode(placeholder, blockquote);
-        setEndingSelection(VisibleSelection(positionBeforeNode(placeholder.get()), DOWNSTREAM, endingSelection().isDirectional()));
+        setEndingSelection(VisibleSelection(positionBeforeNode(placeholder.get()), TextAffinity::Downstream, endingSelection().isDirectional()));
         return;
     }