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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/common_web_contents_delegate.cc
const std::string& url) {
  
  base::StringValue url_value(url);
  web_contents_->CallClientFunction(
      "DevToolsAPI.savedURL", &url_value, nullptr, nullptr);
}
void CommonWebContentsDelegate::OnDevToolsAppendToFile(
    const std::string& url) {
  
  base::StringValue url_value(url);
  web_contents_->CallClientFunction(
      "DevToolsAPI.appendedToURL", &url_value, nullptr, nullptr);
}
void CommonWebContentsDelegate::OnDevToolsIndexingWorkCalculated(