anchor.diff:  const localStorageKeyForQueryParamsPreOAuthRequest = 'gh_pre_auth_query_params';
   const localStorageKeyForGitHubOAuthToken = 'github_oauth_token';
   const localStorageKeyForGitHubUserLogin = 'github_user_login';
  +const queryParamRedirectBeforeLogin = 'initiateGitHubLogin';
   
   class GitHubUIController {
     static const entryPointGitHubOAuthInitiate = 'github_oauth_initiate';
  
positive.code: 
    void _attemptToAquireGitHubToken() {
      // Remember all of our current query params.
      final curUrl = Uri.parse(window.location.toString());
      final params = Map<String, String?>.from(curUrl.queryParameters);
      final jsonParams = json.encode(params);
  
      window.localStorage[localStorageKeyForQueryParamsPreOAuthRequest] =
          jsonParams;
  
  
negative.code:   GitHubUIController(this._playground) {
      _githubAuthController = GitHubAuthenticationController(
          Uri.parse(window.location.toString()), _playground.snackbar);
  
      if (_githubAuthController.delayedGitHubLoginRequested) {
        // A delayed GitHub login has been requested, so initiate it.
        // This occurs when the user was on a NON `dartpad.dev` url,
        // and selected the GitHub login menu.  We must initiate that
        // starting from `dartpad.dev`, so we were redirected to `dartpad.dev`
        // with an added query parameter (defined by [queryParamRedirectBeforeLogin]).
        // This query parameter has been detected and indicates that we should
        // continue as if the user has selected the 'GitHub login' menu.
        _attemptToAquireGitHubToken();
        return;
      }
  
      initGitHubMenu();
      setupGithubGistListeners();
  
  