buffer: remove Uint8Array check

This makes write[U]Int* operations on Buffer with `noAssert=false` about 3
times faster.

PR-URL: nodejs#11324
Refs: nodejs#11245
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Trevor Norris <trev.norris@gmail.com>

lib/buffer.js

@@ -1056,8 +1056,6 @@ Buffer.prototype.readDoubleBE = function readDoubleBE(offset, noAssert) {
 
 
 function checkInt(buffer, value, offset, ext, max, min) {
-  if (!isUint8Array(buffer))
-    throw new TypeError('"buffer" argument must be a Buffer or Uint8Array');
   if (value > max || value < min)
     throw new TypeError('"value" argument is out of bounds');
   if (offset + ext > buffer.length)

test/parallel/test-buffer-write-noassert.js

@@ -20,14 +20,10 @@ function write(funx, args, result, res) {
     );
   }
 
-  {
-    const error = /Int/.test(funx) ?
-      /^TypeError: "buffer" argument must be a Buffer or Uint8Array$/ :
-      /^TypeError: argument should be a Buffer$/;
-
+  if (!/Int/.test(funx)) {
     assert.throws(
       () => Buffer.alloc(9)[funx].apply(new Uint32Array(1), args),
-      error
+      /^TypeError: argument should be a Buffer$/
     );
   }