- Electron version: 1.2.0
- Operating system: Mac OS X - 10.11.5

I upgraded from 1.1.1 to 1.2.0. 1.2.0 breaks on the following `index.html`:

``` html
<!DOCTYPE html>
<html lang="en">
    <head>
        <meta charset="utf-8">
        <script>
            console.log(process.env.NODE_ENV)
        </script>
    </head>
    <body>
        <div id="app-container"></div>
    </body>
</html>
```

Error:

```
Uncaught ReferenceError: process is not defined
```

atom/renderer/atom_renderer_client.cc
content::RenderFrame* render_frame,
    const std::string& mime_type,
    const GURL& original_url) {
  if (mime_type == content::kBrowserPluginMimeType) {
    return new GuestViewContainer(render_frame);
  } else {
    return nullptr;
  }
}
void AtomRendererClient::AddKeySystems(
    std::vector<media::KeySystemInfo>* key_systems) {
  AddChromeKeySystems(key_systems);
}
void AtomRendererClient::GetNavigationErrorStrings(
    content::RenderFrame* render_frame,
    const blink::WebURLRequest& failed_request,
    const blink::WebURLError& error,
    std::string* error_html,
    base::string16* error_description) {
  if (!error_description)
    return;
  *error_description = base::UTF8ToUTF16(net::ErrorToShortString(error.reason));
}
}