stream: avoid getter for defaultEncoding

PR-URL: nodejs#50203
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Yagiz Nizipli <yagiz@nizipli.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>

lib/internal/streams/writable.js

@@ -445,16 +445,17 @@ function _write(stream, chunk, encoding, cb) {
 
   if (typeof encoding === 'function') {
     cb = encoding;
-    encoding = (state[kState] & kDefaultUTF8Encoding) !== 0 ? 'utf8' : state.defaultEncoding;
-  } else {
-    if (!encoding)
-      encoding = (state[kState] & kDefaultUTF8Encoding) !== 0 ? 'utf8' : state.defaultEncoding;
-    else if (encoding !== 'buffer' && !Buffer.isEncoding(encoding))
-      throw new ERR_UNKNOWN_ENCODING(encoding);
-    if (typeof cb !== 'function')
-      cb = nop;
+    encoding = null;
   }
 
+  if (!encoding)
+    encoding = (state[kState] & kDefaultUTF8Encoding) !== 0 ? 'utf8' : state[kDefaultEncodingValue];
+  else if (encoding !== 'buffer' && !Buffer.isEncoding(encoding))
+    throw new ERR_UNKNOWN_ENCODING(encoding);
+
+  if (cb == null || typeof cb !== 'function')
+    cb = nop;
+
   if (chunk === null) {
     throw new ERR_STREAM_NULL_VALUES();
   } else if ((state[kState] & kObjectMode) === 0) {