Introduce enum class TextAffinity as replacement of enum EAffinity

Source/core/editing/EditingUtilities.cpp

Index: Source/core/editing/EditingUtilities.cpp
diff --git a/Source/core/editing/EditingUtilities.cpp b/Source/core/editing/EditingUtilities.cpp
index 313dfc53ac8416ec2b6aca471fd60549d21fec6d..a7ba84ce108e02acdf846ff2a41860ffdadab888 100644
--- a/Source/core/editing/EditingUtilities.cpp
+++ b/Source/core/editing/EditingUtilities.cpp
@@ -1132,7 +1132,7 @@ bool isNodeRendered(const Node& node)
 }
 
 // return first preceding DOM position rendered at a different location, or "this"
-static Position previousCharacterPosition(const Position& position, EAffinity affinity)
+static Position previousCharacterPosition(const Position& position, TextAffinity affinity)
 {
     if (position.isNull())
         return Position();
@@ -1161,7 +1161,7 @@ static Position previousCharacterPosition(const Position& position, EAffinity af
 }
 
 // This assumes that it starts in editable content.
-Position leadingWhitespacePosition(const Position& position, EAffinity affinity, WhitespacePositionOption option)
+Position leadingWhitespacePosition(const Position& position, TextAffinity affinity, WhitespacePositionOption option)
 {
     ASSERT(isEditablePosition(position, ContentIsEditable, DoNotUpdateStyle));
     if (position.isNull())
@@ -1183,7 +1183,7 @@ Position leadingWhitespacePosition(const Position& position, EAffinity affinity,
 }
 
 // This assumes that it starts in editable content.
-Position trailingWhitespacePosition(const Position& position, EAffinity, WhitespacePositionOption option)
+Position trailingWhitespacePosition(const Position& position, TextAffinity, WhitespacePositionOption option)
 {
     ASSERT(isEditablePosition(position, ContentIsEditable, DoNotUpdateStyle));
     if (position.isNull())