buffer: refactor Buffer.prototype.inspect()

Replace toString().match().join() with toString().replace().trim(). This
enables the elimination of a length check becuase replace() will return
empty string if Buffer is empty whereas match() returns null.

PR-URL: nodejs/node#11600
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Yuta Hiroto <hello@about-hiroppy.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>

lib/buffer.js

@@ -513,12 +513,10 @@ Buffer.prototype.equals = function equals(b) {
 Buffer.prototype[internalUtil.customInspectSymbol] = function inspect() {
   var str = '';
   var max = exports.INSPECT_MAX_BYTES;
-  if (this.length > 0) {
-    str = this.toString('hex', 0, max).match(/.{2}/g).join(' ');
-    if (this.length > max)
-      str += ' ... ';
-  }
-  return '<' + this.constructor.name + ' ' + str + '>';
+  str = this.toString('hex', 0, max).replace(/(.{2})/g, '$1 ').trim();
+  if (this.length > max)
+    str += ' ... ';
+  return `<${this.constructor.name} ${str}>`;
 };
 Buffer.prototype.inspect = Buffer.prototype[internalUtil.customInspectSymbol];