Stream 'drain' event now passes the stream as a parameter.

Author: jmalloc

Stream.php

@@ -27,7 +27,7 @@ public function __construct($stream, LoopInterface $loop)
         });
 
         $this->buffer->on('drain', function () {
-            $this->emit('drain');
+            $this->emit('drain', array($this));
         });
 
         $this->resume();