src: remove function hasTextDecoder in encoding.js

also... return TextDecoder directly from factories

PR-URL: https://github.com/nodejs/node/pull/23625
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Сковорода Никита Андреевич <chalkerx@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Sakthipriyan Vairamani <thechargingvolcano@gmail.com>

lib/internal/encoding.js

@@ -341,21 +341,15 @@ Object.defineProperties(
       value: 'TextEncoder'
     } });
 
-const { hasConverter, TextDecoder } =
+const TextDecoder =
   process.binding('config').hasIntl ?
     makeTextDecoderICU() :
     makeTextDecoderJS();
 
-function hasTextDecoder(encoding = 'utf-8') {
-  validateArgument(encoding, 'string', 'encoding', 'string');
-  return hasConverter(getEncodingFromLabel(encoding));
-}
-
 function makeTextDecoderICU() {
   const {
     decode: _decode,
     getConverter,
-    hasConverter
   } = internalBinding('icu');
 
   class TextDecoder {
@@ -409,7 +403,7 @@ function makeTextDecoderICU() {
     }
   }
 
-  return { hasConverter, TextDecoder };
+  return TextDecoder;
 }
 
 function makeTextDecoderJS() {
@@ -497,7 +491,7 @@ function makeTextDecoderJS() {
     }
   }
 
-  return { hasConverter, TextDecoder };
+  return TextDecoder;
 }
 
 // Mix in some shared properties.
@@ -552,7 +546,6 @@ function makeTextDecoderJS() {
 
 module.exports = {
   getEncodingFromLabel,
-  hasTextDecoder,
   TextDecoder,
   TextEncoder
 };