[fix] dont use bind in the one case we do

Author: jcrugzz

Diff for: lib/http-proxy/index.js

@@ -104,7 +104,7 @@ function ProxyServer(options) {
     return ws[pass];
   });
 
-  this.on('error', this.onError.bind(this));
+  this.on('error', this.onError, this);
 
 }