* **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
content::BrowserContext* browser_context,
    const GURL& url,
    content::RenderFrameHost* rfh) const {
  std::string affinity = GetAffinityPreference(rfh);
  if (!affinity.empty()) {
    auto iter = site_per_affinities_.find(affinity);
    GURL dest_site = content::SiteInstance::GetSiteForURL(browser_context, url);
    if (iter != site_per_affinities_.end() &&
        IsSameWebSite(browser_context, iter->second, dest_site)) {
      return iter->second;
    }
  }
  return nullptr;
}
void AtomBrowserClient::ConsiderSiteInstanceForAffinity(
    content::RenderFrameHost* rfh,
    content::SiteInstance* site_instance) {
  std::string affinity = GetAffinityPreference(rfh);
  if (!affinity.empty()) {
    site_per_affinities_[affinity] = site_instance;
  }
}
void AtomBrowserClient::RenderProcessWillLaunch(