Introduce enum class TextAffinity as replacement of enum EAffinity

Source/core/editing/EditingUtilities.h

Index: Source/core/editing/EditingUtilities.h
diff --git a/Source/core/editing/EditingUtilities.h b/Source/core/editing/EditingUtilities.h
index 8483fbf3e3a5145006796bdb6487fc1d0bcaf2fd..410d40ff3919d8a890ada433f194a78670fdbc18 100644
--- a/Source/core/editing/EditingUtilities.h
+++ b/Source/core/editing/EditingUtilities.h
@@ -200,8 +200,8 @@ bool isAtUnsplittableElement(const Position&);
 // miscellaneous functions on Position
 
 enum WhitespacePositionOption { NotConsiderNonCollapsibleWhitespace, ConsiderNonCollapsibleWhitespace };
-Position leadingWhitespacePosition(const Position&, EAffinity, WhitespacePositionOption = NotConsiderNonCollapsibleWhitespace);
-Position trailingWhitespacePosition(const Position&, EAffinity, WhitespacePositionOption = NotConsiderNonCollapsibleWhitespace);
+Position leadingWhitespacePosition(const Position&, TextAffinity, WhitespacePositionOption = NotConsiderNonCollapsibleWhitespace);
+Position trailingWhitespacePosition(const Position&, TextAffinity, WhitespacePositionOption = NotConsiderNonCollapsibleWhitespace);
 unsigned numEnclosingMailBlockquotes(const Position&);
 void updatePositionForNodeRemoval(Position&, Node&);