Remove dedicated TextCodecUTF16

Source/modules/encoding/TextEncoder.cpp

Index: Source/modules/encoding/TextEncoder.cpp
diff --git a/Source/modules/encoding/TextEncoder.cpp b/Source/modules/encoding/TextEncoder.cpp
index 5d3674813d54026d8a127af4188c631f81e7871c..d196f5cc42622ffd3253921387b9a53a12abe2a9 100644
--- a/Source/modules/encoding/TextEncoder.cpp
+++ b/Source/modules/encoding/TextEncoder.cpp
@@ -47,7 +47,7 @@ TextEncoder* TextEncoder::create(const String& utfLabel, ExceptionState& excepti
     }
 
     String name(encoding.name());
-    if (name != "UTF-8" && name != "UTF-16LE" && name != "UTF-16BE") {
+    if (name != "UTF-8" && name != "utf-16le" && name != "utf-16be") {
         exceptionState.throwRangeError("The encoding provided ('" + utfLabel + "') is not one of 'utf-8', 'utf-16', or 'utf-16be'.");
         return 0;
     }