stream: guard ArrayBuffer normalization and simplify test

Author: suuuuuuminnnnnn

lib/internal/webstreams/adapters.js

@@ -217,7 +217,7 @@ function newWritableStreamFromStreamWritable(streamWritable) {
     start(c) { controller = c; },
 
     write(chunk) {
-      if (isArrayBuffer(chunk)) {
+      if (!streamWritable.writableObjectMode && isArrayBuffer(chunk)) {
         chunk = new Uint8Array(chunk);
       }
       if (streamWritable.writableNeedDrain || !streamWritable.write(chunk)) {

test/parallel/test-webstreams-compression-buffer-source.js

@@ -43,16 +43,7 @@ async function testCompressionRoundTripWithArrayBuffer() {
   await csWriter.write(input);
   csWriter.close();
 
-  const compressed = [];
-  let done = false;
-  while (!done) {
-    const { value, done: d } = await csReader.read();
-    if (value) compressed.push(value);
-    done = d;
-  }
-
-  for (const chunk of compressed) await dsWriter.write(chunk);
-  dsWriter.close();
+  await cs.readable.pipeTo(ds.writable);
 
   const out = [];
   done = false;