* Electron version: 2.0.0-beta.4
* Operating system: macOS 10.13.3

### Expected behavior

A reload of the window works.

### Actual behavior

A reload of the window does not work.

### How to reproduce

* run VSCode exploration ([download](https://az764295.vo.msecnd.net/exploration/6bc3274250cc949c7fb1d654cbb6e59c8ddad697/VSCode-darwin-exploration.zip))
* run "Reload Window" command
* sometimes I see the window stay blank after doing so and checking the console I see:

```
Uncaught (in promise) Error: Cannot get property 'id' on missing remote object 3
Error: Cannot get property 'id' on missing remote object 3
    at throwRPCError (/Applications/Visual Studio Code - Exploration.app/Contents/Resources/electron.asar/browser/rpc-server.js:143:17)
    at EventEmitter.<anonymous> (/Applications/Visual Studio Code - Exploration.app/Contents/Resources/electron.asar/browser/rpc-server.js:384:7)
    at emitThree (events.js:136:13)
    at EventEmitter.emit (events.js:217:7)
    at WebContents.<anonymous> (/Applications/Visual Studio Code - Exploration.app/Contents/Resources/electron.asar/browser/api/web-contents.js:295:13)
    at emitTwo (events.js:126:13)
    at WebContents.emit (events.js:214:7)
    at throwRPCError (/Applications/Visual Studio Code - Exploration.app/Contents/Resources/electron.asar/browser/rpc-server.js:143:17)
    at EventEmitter.<anonymous> (/Applications/Visual Studio Code - Exploration.app/Contents/Resources/electron.asar/browser/rpc-server.js:384:7)
    at emitThree (events.js:136:13)
    at EventEmitter.emit (events.js:217:7)
    at WebContents.<anonymous> (/Applications/Visual Studio Code - Exploration.app/Contents/Resources/electron.asar/browser/api/web-contents.js:295:13)
    at emitTwo (events.js:126:13)
    at WebContents.emit (events.js:214:7)
    at Object.exception (/Applications/Visual Studio Code - Exploration.app/Contents/Resources/electron.asar/renderer/api/remote.js:209:30)
    at metaToValue (/Applications/Visual Studio Code - Exploration.app/Contents/Resources/electron.asar/renderer/api/remote.js:213:28)
    at Object.descriptor.get [as id] (/Applications/Visual Studio Code - Exploration.app/Contents/Resources/electron.asar/renderer/api/remote.js:132:16)
    at file:///Applications/Visual%20Studio%20Code%20-%20Exploration.app/Contents/Resources/app/out/vs/workbench/electron-browser/bootstrap/index.js:11:97
    at new Promise (<anonymous>)
    at file:///Applications/Visual%20Studio%20Code%20-%20Exploration.app/Contents/Resources/app/out/vs/workbench/electron-browser/bootstrap/index.js:10:838
```
atom/browser/atom_browser_client.cc
auto it = process_preferences_.find(process_id);
  return it != process_preferences_.end() && it->second.disable_popups;
}
void AtomBrowserClient::RenderProcessWillLaunch(
    content::RenderProcessHost* host) {
  
  int process_id = host->GetID();
  if (IsProcessObserved(process_id))
    return;
  host->AddFilter(new printing::PrintingMessageFilter(process_id));
  host->AddFilter(new TtsMessageFilter(process_id, host->GetBrowserContext()));
  host->AddFilter(
      new WidevineCdmMessageFilter(process_id, host->GetBrowserContext()));
  content::WebContents* web_contents = GetWebContentsFromProcessID(process_id);
  ProcessPreferences process_prefs;
  process_prefs.sandbox =
      WebContentsPreferences::IsPreferenceEnabled("sandbox", web_contents);
  process_prefs.native_window_open =
      WebContentsPreferences::IsPreferenceEnabled("nativeWindowOpen",
                                                  web_contents);
  process_prefs.disable_popups =
      WebContentsPreferences::IsPreferenceEnabled("disablePopups",
                                                  web_contents);
  AddProcessPreferences(host->GetID(), process_prefs);
  
  host->AddObserver(this);
}
content::SpeechRecognitionManagerDelegate*