* **Electron Version** (output of `node_modules/.bin/electron --version`):
  * 3.0.6
* **Operating System** (Platform and Version):
  * macOS 10.14

### Expected Behavior
a `new-window` event fires

### Actual behavior
a `did-fail-load` fires with errorCode -3

### To Reproduce
```sh
$ git clone git@github.com:chrismohr/no-new-window.git -b master
$ cd no-new-window/
$ npm i && npm start
```

atom/browser/atom_browser_client.cc
if (!ShouldForceNewSiteInstance(current_rfh, speculative_rfh, browser_context,
                                  url, has_response_started)) {
    return SiteInstanceForNavigationType::ASK_CHROMIUM;
  }
  
  
  
  
  
  
  
  
  
  
  if (has_response_started) {
    return SiteInstanceForNavigationType::FORCE_CURRENT;
  }
  return SiteInstanceForNavigationType::FORCE_CANDIDATE_OR_NEW;
}
void AtomBrowserClient::RegisterPendingSiteInstance(
    content::RenderFrameHost* rfh,
    content::SiteInstance* pending_site_instance) {
  
  ConsiderSiteInstanceForAffinity(rfh, pending_site_instance);
  
  auto* web_contents = content::WebContents::FromRenderFrameHost(rfh);
  auto* pending_process = pending_site_instance->GetProcess();
  pending_processes_[pending_process->GetID()] = web_contents;
}
void AtomBrowserClient::AppendExtraCommandLineSwitches(