Patch: fix buffer() warning

Hi,

Could you please apply:
```
commit 07277d8b164659247901085ab1fc63b8e18586f1 (HEAD -> patched)
Author: Bastien Roucariès
Date: Mon Jan 7 01:16:24 2019 +0100

Fix Buffer warning

diff --git a/test/buf.js b/test/buf.js
index 8217819..d7c37eb 100644
--- a/test/buf.js
+++ b/test/buf.js
@@ -18,7 +18,7 @@ TestWritable.prototype._write = function(chunk, encoding, cb) {
cb();
};

-var buf = Buffer([ 88 ]);
+var buf = Buffer.from([ 88 ]);

test('.writable writing ArrayBuffer', function(t) {
var writable = new TestWritable();
```