[0.14.5 sdk]inject_js_start not work

version: 0.14.5
os: Windows

test code:

```
// package.json
{
  "main": "http://www.qq.com",
  "inject_js_start": "demo.js",
  "name": "menu demo",
  "window": {
    "width": 700,
    "height": 700
  }
}
```

```
// demo.js
alert('hello inject_js_start')
```

0.14.5 inject_js_start not work. can not alert "hello inject_js_star"
