### 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
Browser::LaunchItem val) {
    gin_helper::Dictionary dict = gin::Dictionary::CreateEmpty(isolate);
    dict.Set("name", val.name);
    dict.Set("path", val.path);
    dict.Set("args", val.args);
    dict.Set("scope", val.scope);
    dict.Set("enabled", val.enabled);
    return dict.GetHandle();
  }
};
#endif
template <>
struct Converter<Browser::LoginItemSettings> {
  static bool FromV8(v8::Isolate* isolate,
                     v8::Local<v8::Value> val,
                     Browser::LoginItemSettings* out) {
    gin_helper::Dictionary dict;
    if (!ConvertFromV8(isolate, val, &dict))
      return false;
    dict.Get("openAtLogin", &(out->open_at_login));
    dict.Get("openAsHidden", &(out->open_as_hidden));
    dict.Get("path", &(out->path));
    dict.Get("args", &(out->args));
#if defined(OS_WIN)
    dict.Get("enabled", &(out->enabled));
    dict.Get("name", &(out->name));
#endif
    return true;
  }
  static v8::Local<v8::Value> ToV8(v8::Isolate* isolate,