### 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
v8::Local<v8::Value> val,
                     JumpListItem::Type* out) {
    std::string item_type;
    if (!ConvertFromV8(isolate, val, &item_type))
      return false;
    if (item_type == "task")
      *out = JumpListItem::Type::kTask;
    else if (item_type == "separator")
      *out = JumpListItem::Type::kSeparator;
    else if (item_type == "file")
      *out = JumpListItem::Type::kFile;
    else
      return false;
    return true;
  }
  static v8::Local<v8::Value> ToV8(v8::Isolate* isolate,