Causes a continuous increase in memory usage
I am a Sketch Plug-in developer.

**Expected behavior:**

Sketch occupies almost no fluctuation in memory usage each time the plugin command containing `react-sketchapp` is called.

**Observed behavior:**

Each call to the command increases Sketch's non-recoverable memory footprint

**How to reproduce:**

See  [antd-sketchapp](https://github.com/ant-design/antd-sketchapp/blob/master/docs/en-us/development.md#how-to-preview) demo.

**Sketch version:**

All versions.

**Please attach screenshots, a zip file of your project, and/or a link to your github project**

![kapture 2018-03-14 at 16 27 43](https://user-images.githubusercontent.com/2953176/37391010-e9333e6c-27a4-11e8-8783-723fcc1bbf3b.gif)