Remove dedicated TextCodecUTF16

Source/wtf/text/TextCodecICU.cpp

Index: Source/wtf/text/TextCodecICU.cpp
diff --git a/Source/wtf/text/TextCodecICU.cpp b/Source/wtf/text/TextCodecICU.cpp
index f24dda0aad8b3c5815412c9fa482637dead11346..c5f60346f3379bd86f13f558404a1564d4a0bc10 100644
--- a/Source/wtf/text/TextCodecICU.cpp
+++ b/Source/wtf/text/TextCodecICU.cpp
@@ -212,6 +212,16 @@ void TextCodecICU::registerEncodingNames(EncodingNameRegistrar registrar)
     registrar("x-cp1256", "windows-1256");
     registrar("x-cp1257", "windows-1257");
     registrar("x-cp1258", "windows-1258");
+
+    // Standard labels for UTF-16.
+    registrar("UTF-16", "utf-16le");
+    // Non-standard labels for UTF-16.
+    registrar("ISO-10646-UCS-2", "utf-16le");
+    registrar("UCS-2", "utf-16le");
+    registrar("Unicode", "utf-16le");
+    registrar("csUnicode", "utf-16le");
+    registrar("unicodeFEFF", "utf-16le");
+    registrar("unicodeFFFE", "utf-16be");
 }
 
 void TextCodecICU::registerCodecs(TextCodecRegistrar registrar)
@@ -487,7 +497,8 @@ CString TextCodecICU::encodeInternal(const TextCodecInput& input, UnencodableHan
 
     switch (handling) {
         case QuestionMarksForUnencodables:
-            ucnv_setSubstChars(m_converterICU, "?", 1, &err);
+            if (!m_encoding.isNonByteBasedEncoding())
+                ucnv_setSubstChars(m_converterICU, "?", 1, &err);
             ucnv_setFromUCallBack(m_converterICU, m_needsGBKFallbacks ? gbkCallbackSubstitute : UCNV_FROM_U_CALLBACK_SUBSTITUTE, 0, 0, 0, &err);
             break;
         case EntitiesForUnencodables: