Error when running with jest

还没有人认领这个 Issue。

```js
console.error node_modules/jsdom-worker/dist/jsdom-inline-worker.js:1
Error: only absolute urls are supported
at /Users/aaronvasquez/Oyster/webnode/directories/node_modules/node-fetch/index.js:54:10
at new Promise ()
at new Fetch (/Users/aaronvasquez/Oyster/webnode/directories/node_modules/node-fetch/index.js:49:9)
at Fetch (/Users/aaronvasquez/Oyster/webnode/directories/node_modules/node-fetch/index.js:37:10)
at Object..global.fetch (/Users/aaronvasquez/Oyster/webnode/directories/node_modules/jsdom-worker/dist/jsdom-inline-worker.js:1:876)
at new Worker (/Users/aaronvasquez/Oyster/webnode/directories/node_modules/jsdom-worker/dist/jsdom-inline-worker.js:1:1780)
at /Users/aaronvasquez/Oyster/webnode/directories/src/utils/bg-worker/index.js:12:29
at new Promise ()
at performTask (/Users/aaronvasquez/Oyster/webnode/directories/src/utils/bg-worker/index.js:11:5)
at Object. (/Users/aaronvasquez/Oyster/webnode/directories/src/utils/bg-worker/bg-worker.test.js:9:29)
at resolve (/Users/aaronvasquez/Oyster/webnode/directories/node_modules/jest-jasmine2/build/queueRunner.js:38:12)
at new Promise ()
at mapper (/Users/aaronvasquez/Oyster/webnode/directories/node_modules/jest-jasmine2/build/queueRunner.js:31:21)
at Promise.resolve.then.el (/Users/aaronvasquez/Oyster/webnode/directories/node_modules/p-map/index.js:46:16)
at
at process._tickCallback (internal/process/next_tick.js:188:7)
```

This is what I have in my test file:
```js
import "jsdom-worker";
```

首先运行 src/utils/bg-worker/bg-worker.test.js 并阅读 src/utils/bg-worker/index.js，重点关注 stack trace 中显示的 Worker 构造过程。跟踪导入 jsdom-worker 如何导致 node-fetch 接收到非绝对 URL；当 Jest 测试在没有此错误的情况下运行并保留其预期行为时，即表示完成。

由索引模型根据 Issue 内容生成。