Remove dedicated TextCodecUTF16

Source/wtf/text/TextEncoding.h

Index: Source/wtf/text/TextEncoding.h
diff --git a/Source/wtf/text/TextEncoding.h b/Source/wtf/text/TextEncoding.h
index 058b3edfbb83af10315be442249d9aaaaa8d3bb1..b12fa20771322cd089267ff635d491d57d3e8288 100644
--- a/Source/wtf/text/TextEncoding.h
+++ b/Source/wtf/text/TextEncoding.h
@@ -42,6 +42,7 @@ public:
     bool isValid() const { return m_name; }
     const char* name() const { return m_name; }
     bool usesVisualOrdering() const;
+    bool isNonByteBasedEncoding() const;
     const TextEncoding& closestByteBasedEquivalent() const;
     const TextEncoding& encodingForFormSubmission() const;
 
@@ -59,7 +60,6 @@ public:
     CString normalizeAndEncode(const String&, UnencodableHandling) const;
 
 private:
-    bool isNonByteBasedEncoding() const;
     bool isUTF7Encoding() const;
 
     const char* m_name;