Introduce enum class TextAffinity as replacement of enum EAffinity

Source/core/layout/LayoutBlock.cpp

Index: Source/core/layout/LayoutBlock.cpp
diff --git a/Source/core/layout/LayoutBlock.cpp b/Source/core/layout/LayoutBlock.cpp
index a223473fa405dbae5379120b27cf048de8a4e744..116c979367c9b7c7fc0eb820d6eeff761531ee70 100644
--- a/Source/core/layout/LayoutBlock.cpp
+++ b/Source/core/layout/LayoutBlock.cpp
@@ -1823,7 +1823,7 @@ static PositionWithAffinity positionForPointRespectingEditingBoundaries(LayoutBl
     LayoutUnit logicalLeft = parent->isHorizontalWritingMode() ? pointInChildCoordinates.x() : pointInChildCoordinates.y();
     if (logicalLeft < childMiddle)
         return ancestor->createPositionWithAffinity(childNode->nodeIndex());
-    return ancestor->createPositionWithAffinity(childNode->nodeIndex() + 1, UPSTREAM);
+    return ancestor->createPositionWithAffinity(childNode->nodeIndex() + 1, TextAffinity::Upstream);
 }
 
 PositionWithAffinity LayoutBlock::positionForPointWithInlineChildren(const LayoutPoint& pointInLogicalContents)