### Preflight Checklist

- [X] I have read the [Contributing Guidelines](https://github.com/electron/electron/blob/master/CONTRIBUTING.md) for this project.
- [X] I agree to follow the [Code of Conduct](https://github.com/electron/electron/blob/master/CODE_OF_CONDUCT.md) that this project adheres to.
- [X] I have searched the [issue tracker](https://www.github.com/electron/electron/issues) for a feature request that matches the one I want to file, without success.

### Problem Description

We need to load a custom error page when the certificate is invalid but without "isMainFrame" property we don't know when to load the custom error page using webContents.loadURL()

### Proposed Solution

webContents.on("certificate-error", ((event, url, error, certificate, callback, isMainFrame)

### Alternatives Considered

Not sure

### Additional Information

Not sure
shell/browser/api/electron_api_app.cc
.SetMethod("hide", base::BindRepeating(&Browser::Hide, browser))
      .SetMethod("show", base::BindRepeating(&Browser::Show, browser))
      .SetMethod("setUserActivity",
                 base::BindRepeating(&Browser::SetUserActivity, browser))
      .SetMethod("getCurrentActivityType",
                 base::BindRepeating(&Browser::GetCurrentActivityType, browser))
      .SetMethod(
          "invalidateCurrentActivity",
          base::BindRepeating(&Browser::InvalidateCurrentActivity, browser))
      .SetMethod("resignCurrentActivity",
                 base::BindRepeating(&Browser::ResignCurrentActivity, browser))
      .SetMethod("updateCurrentActivity",
                 base::BindRepeating(&Browser::UpdateCurrentActivity, browser))
      .SetMethod("moveToApplicationsFolder", &App::MoveToApplicationsFolder)
      .SetMethod("isInApplicationsFolder", &App::IsInApplicationsFolder)
      .SetMethod("setActivationPolicy", &App::SetActivationPolicy)
#endif
      .SetMethod("setAboutPanelOptions",
                 base::BindRepeating(&Browser::SetAboutPanelOptions, browser))
      .SetMethod("showAboutPanel",
                 base::BindRepeating(&Browser::ShowAboutPanel, browser))
#if defined(OS_MAC)
      .SetMethod(
          "isSecureKeyboardEntryEnabled",
          base::BindRepeating(&Browser::IsSecureKeyboardEntryEnabled, browser))
      .SetMethod(
          "setSecureKeyboardEntryEnabled",
          base::BindRepeating(&Browser::SetSecureKeyboardEntryEnabled, browser))
#endif
#if defined(OS_MAC) || defined(OS_WIN)