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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
GoToOffset(offset);
  return false;
}
void WebContents::FindReply(content::WebContents* web_contents,
                            int request_id,
                            int number_of_matches,
                            const gfx::Rect& selection_rect,
                            int active_match_ordinal,
                            bool final_update) {
  if (!final_update)
    return;
  v8::Locker locker(isolate());
  v8::HandleScope handle_scope(isolate());
  mate::Dictionary result = mate::Dictionary::CreateEmpty(isolate());
  result.Set("requestId", request_id);
  result.Set("matches", number_of_matches);
  result.Set("selectionArea", selection_rect);
  result.Set("activeMatchOrdinal", active_match_ordinal);
  result.Set("finalUpdate", final_update);  
  Emit("found-in-page", result);
}
bool WebContents::CheckMediaAccessPermission(