Introduce enum class TextAffinity as replacement of enum EAffinity

Source/core/editing/commands/InsertLineBreakCommand.cpp

Index: Source/core/editing/commands/InsertLineBreakCommand.cpp
diff --git a/Source/core/editing/commands/InsertLineBreakCommand.cpp b/Source/core/editing/commands/InsertLineBreakCommand.cpp
index 4539d2996449ce9a809c698429a543ce1665f563..1b0e53bb57e1729d33aa670ce9107404f45e6c30 100644
--- a/Source/core/editing/commands/InsertLineBreakCommand.cpp
+++ b/Source/core/editing/commands/InsertLineBreakCommand.cpp
@@ -108,12 +108,12 @@ void InsertLineBreakCommand::doApply()
         if (!isStartOfParagraph(VisiblePosition(positionBeforeNode(nodeToInsert.get()))))
             insertNodeBefore(nodeToInsert->cloneNode(false).get(), nodeToInsert.get());
 
-        setEndingSelection(VisibleSelection(positionInParentAfterNode(*nodeToInsert), DOWNSTREAM, endingSelection().isDirectional()));
+        setEndingSelection(VisibleSelection(positionInParentAfterNode(*nodeToInsert), TextAffinity::Downstream, endingSelection().isDirectional()));
     // If we're inserting after all of the rendered text in a text node, or into a non-text node,
     // a simple insertion is sufficient.
     } else if (!pos.anchorNode()->isTextNode() || pos.computeOffsetInContainerNode() >= caretMaxOffset(pos.anchorNode())) {
         insertNodeAt(nodeToInsert.get(), pos);
-        setEndingSelection(VisibleSelection(positionInParentAfterNode(*nodeToInsert), DOWNSTREAM, endingSelection().isDirectional()));
+        setEndingSelection(VisibleSelection(positionInParentAfterNode(*nodeToInsert), TextAffinity::Downstream, endingSelection().isDirectional()));
     } else if (pos.anchorNode()->isTextNode()) {
         // Split a text node
         Text* textNode = toText(pos.anchorNode());
@@ -140,7 +140,7 @@ void InsertLineBreakCommand::doApply()
             }
         }
 
-        setEndingSelection(VisibleSelection(endingPosition, DOWNSTREAM, endingSelection().isDirectional()));
+        setEndingSelection(VisibleSelection(endingPosition, TextAffinity::Downstream, endingSelection().isDirectional()));
     }
 
     // Handle the case where there is a typing style.