### 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
std::string result_code;
    switch (val) {
      case JumpListResult::kSuccess:
        result_code = "ok";
        break;
      case JumpListResult::kArgumentError:
        result_code = "argumentError";
        break;
      case JumpListResult::kGenericError:
        result_code = "error";
        break;
      case JumpListResult::kCustomCategorySeparatorError:
        result_code = "invalidSeparatorError";
        break;
      case JumpListResult::kMissingFileTypeRegistrationError:
        result_code = "fileTypeRegistrationError";
        break;
      case JumpListResult::kCustomCategoryAccessDeniedError:
        result_code = "customCategoryAccessDeniedError";
        break;
    }
    return ConvertToV8(isolate, result_code);
  }
};
#endif
#if defined(OS_WIN)
template <>
struct Converter<Browser::LaunchItem> {
  static bool FromV8(v8::Isolate* isolate,