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* 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/api/atom_api_web_contents.cc
: embedder_(nullptr),
      zoom_controller_(nullptr),
      type_(BROWSER_WINDOW),
      request_id_(0),
      background_throttling_(true),
      enable_devtools_(true) {
  
  options.Get("backgroundThrottling", &background_throttling_);
  
  
  
  
  
  bool b = false;
  if (options.Get("isGuest", &b) && b)
    type_ = WEB_VIEW;
  else if (options.Get("isBackgroundPage", &b) && b)
    type_ = BACKGROUND_PAGE;
  else if (options.Get("offscreen", &b) && b)
    type_ = OFF_SCREEN;
  
  options.Get("devTools", &enable_devtools_);
  
  std::string partition;
  mate::Handle<api::Session> session;
  if (options.Get("session", &session)) {
  } else if (options.Get("partition", &partition)) {
    session = Session::FromPartition(isolate, partition);
  } else {