buffer: avoid materializing ArrayBuffer for creation

Do not create an `ArrayBuffer` if the engine’s settings avoid it
and we don’t need it.

PR-URL: #26301
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

lib/buffer.js

@@ -106,21 +106,17 @@ let poolSize, poolOffset, allocPool;
 const zeroFill = bindingZeroFill || [0];
 
 function createUnsafeBuffer(size) {
- return new FastBuffer(createUnsafeArrayBuffer(size));
-}
-
-function createUnsafeArrayBuffer(size) {
  zeroFill[0] = 0;
  try {
- return new ArrayBuffer(size);
+ return new FastBuffer(size);
  } finally {
  zeroFill[0] = 1;
  }
 }
 
 function createPool() {
  poolSize = Buffer.poolSize;
- allocPool = createUnsafeArrayBuffer(poolSize);
+ allocPool = createUnsafeBuffer(poolSize).buffer;
  poolOffset = 0;
 }
 createPool();