zlib: use Buffer.concat()

lib/zlib.js

@@ -150,25 +150,7 @@ function zlibBuffer(engine, buffer, callback) {
   }
 
   function onEnd() {
-    var buffer;
-    switch (buffers.length) {
-      case 0:
-        buffer = new Buffer(0);
-        break;
-      case 1:
-        buffer = buffers[0];
-        break;
-      default:
-        buffer = new Buffer(nread);
-        var n = 0;
-        buffers.forEach(function(b) {
-          var l = b.length;
-          b.copy(buffer, n, 0, l);
-          n += l;
-        });
-        break;
-    }
-    callback(null, buffer);
+    callback(null, Buffer.concat(buffers, nread));
   }
 
   engine.on('error', onError);