<!--
Thanks for opening an issue! A few things to keep in mind:

- The issue tracker is only for bugs and feature requests.
- Before reporting a bug, please try reproducing your issue against
  the latest version of Electron.
- If you need general advice, join our Slack: http://atom-slack.herokuapp.com
-->

* Electron version: 1.6.1
* Operating system: macOS

### Expected behavior

navigator.geolocation.getCurrentPosition runs in background

### Actual behavior

the entire UI is frozen

### How to reproduce

```js
    navigator.geolocation.getCurrentPosition((pos) => {
      console.log('POS: ' + pos);
    }, (err) => {
      console.log('Geolocation error: ', err);
    }, {enableHighAccuracy: false});
```
atom/browser/common_web_contents_delegate.cc
if (enter_fullscreen && owner_window_->IsFullscreen()) {
    native_fullscreen_ = true;
    html_fullscreen_ = true;
    return;
  }
  
  if (!enter_fullscreen && native_fullscreen_) {
    html_fullscreen_ = false;
    return;
  }
  owner_window_->SetFullScreen(enter_fullscreen);
  html_fullscreen_ = enter_fullscreen;
  native_fullscreen_ = false;
}
}