- 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
public:
  AtomRenderFrameObserver(content::RenderFrame* frame,
                          AtomRendererClient* renderer_client)
      : content::RenderFrameObserver(frame),
        render_frame_(frame),
        world_id_(-1),
        renderer_client_(renderer_client) {}
  
  void DidCreateScriptContext(v8::Handle<v8::Context> context,
                              int extension_group,
                              int world_id) override {
    if (world_id_ != -1 && world_id_ != world_id)
      return;
    world_id_ = world_id;
    renderer_client_->DidCreateScriptContext(context, render_frame_);
  }
  void WillReleaseScriptContext(v8::Local<v8::Context> context,
                                int world_id) override {
    if (world_id_ != world_id)
      return;
    renderer_client_->WillReleaseScriptContext(context, render_frame_);
  }
 private:
  content::RenderFrame* render_frame_;
  int world_id_;
  AtomRendererClient* renderer_client_;
  DISALLOW_COPY_AND_ASSIGN(AtomRenderFrameObserver);
};
v8::Local<v8::Value> GetRenderProcessPreferences(