stream: simplify uint8ArrayToBuffer helper

The fallback code is no longer used when exporting to readable-stream.

Refs: #29514

PR-URL: #30041
Fixes: #30040
Reviewed-By: Yongsheng Zhang <zyszys98@gmail.com>
Reviewed-By: David Carlier <devnexen@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Jiawen Geng <technicalcute@gmail.com>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>

lib/stream.js

@@ -21,9 +21,9 @@
 
 'use strict';
 
-const { Buffer } = require('buffer');
 const pipeline = require('internal/streams/pipeline');
 const eos = require('internal/streams/end-of-stream');
+const internalBuffer = require('internal/buffer');
 
 // Note: export Stream before Readable/Writable/Duplex/...
 // to avoid a cross-reference(require) issues
@@ -42,19 +42,8 @@ Stream.finished = eos;
 Stream.Stream = Stream;
 
 Stream._isUint8Array = require('internal/util/types').isUint8Array;
-
-try {
-  const internalBuffer = require('internal/buffer');
-  Stream._uint8ArrayToBuffer = function _uint8ArrayToBuffer(chunk) {
-    return new internalBuffer.FastBuffer(chunk.buffer,
-                                         chunk.byteOffset,
-                                         chunk.byteLength);
-  };
-} catch (e) { // eslint-disable-line no-unused-vars
-}
-
-if (!Stream._uint8ArrayToBuffer) {
-  Stream._uint8ArrayToBuffer = function _uint8ArrayToBuffer(chunk) {
-    return Buffer.prototype.slice.call(chunk);
-  };
-}
+Stream._uint8ArrayToBuffer = function _uint8ArrayToBuffer(chunk) {
+  return new internalBuffer.FastBuffer(chunk.buffer,
+                                       chunk.byteOffset,
+                                       chunk.byteLength);
+};