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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.h
bool IsLoading() const;
  bool IsLoadingMainFrame() const;
  bool IsWaitingForResponse() const;
  void Stop();
  void ReloadIgnoringCache();
  void GoBack();
  void GoForward();
  void GoToOffset(int offset);
  const std::string GetWebRTCIPHandlingPolicy() const;
  void SetWebRTCIPHandlingPolicy(const std::string& webrtc_ip_handling_policy);
  bool IsCrashed() const;
  void SetUserAgent(const std::string& user_agent, mate::Arguments* args);
  std::string GetUserAgent();
  void InsertCSS(const std::string& css);
  bool SavePage(const base::FilePath& full_file_path,
                const content::SavePageType& save_type,
                const SavePageHandler::SavePageCallback& callback);
  void OpenDevTools(mate::Arguments* args);
  void CloseDevTools();
  bool IsDevToolsOpened();
  bool IsDevToolsFocused();
  void ToggleDevTools();
  void EnableDeviceEmulation(const blink::WebDeviceEmulationParams& params);
  void DisableDeviceEmulation();
  void InspectElement(int x, int y);
  void InspectServiceWorker();
  void HasServiceWorker(const base::Callback<void(bool)>&);
  void UnregisterServiceWorker(const base::Callback<void(bool)>&);
  void SetAudioMuted(bool muted);
  bool IsAudioMuted();