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### Issue Details
`webContents.openDevTools();` produces error:
`[12703:1102/100312.745262:ERROR:CONSOLE(1)] "Uncaught TypeError: Cannot read property 'setDockSide' of undefined", source: devtools://devtools/bundled/devtools_app.html?remoteBase=https://chrome-devtools-frontend.appspot.com/serve_file/@1eb8474cd7e4fccfbfa8048eceda1eab8b4d394/&can_dock=true&toolbarColor=rgba(223,223,223,1)&textColor=rgba(0,0,0,1)&experiments=true (1)`

Opening dev tools via these methods also produces the same error:
* Right click background > Inspect element
* Ctrl-Shift-I

* **Electron Version:**
  * 11.0.0-beta.18
* **Operating System:**
  * Debian 10 Buster x64, KDE Plasma
* **Last Known Working Electron version:**
  * 10.1.4

### Expected Behavior
Dev tools should open without error.

### Actual Behavior
Above error appears in the terminal.

### To Reproduce
Running this code will probably do it, although I'm opening a URL, but that shouldn't matter.
https://www.electronjs.org/docs/tutorial/quick-start#create-a-basic-application

### Additional Information
I need the beta because the stable version's node is too old.
shell/browser/ui/inspectable_web_contents.cc
int stream_id,
      InspectableWebContents* bindings,
      const network::ResourceRequest& resource_request,
      const net::NetworkTrafficAnnotationTag& traffic_annotation,
      URLLoaderFactoryHolder url_loader_factory,
      const DispatchCallback& callback,
      base::TimeDelta delay)
      : stream_id_(stream_id),
        bindings_(bindings),
        resource_request_(resource_request),
        traffic_annotation_(traffic_annotation),
        loader_(network::SimpleURLLoader::Create(
            std::make_unique<network::ResourceRequest>(resource_request),
            traffic_annotation)),
        url_loader_factory_(std::move(url_loader_factory)),
        callback_(callback),
        retry_delay_(delay) {
    loader_->SetOnResponseStartedCallback(base::BindOnce(
        &NetworkResourceLoader::OnResponseStarted, base::Unretained(this)));
    timer_.Start(FROM_HERE, delay,
                 base::BindRepeating(&NetworkResourceLoader::DownloadAsStream,
                                     base::Unretained(this)));
  }
  NetworkResourceLoader(const NetworkResourceLoader&) = delete;
  NetworkResourceLoader& operator=(const NetworkResourceLoader&) = delete;
 private:
  void DownloadAsStream() {
    loader_->DownloadAsStream(url_loader_factory_.get(), this);
  }
  base::TimeDelta GetNextExponentialBackoffDelay(const base::TimeDelta& delta) {