* Output of `node_modules/.bin/electron --version`: v4.0.0
* Operating System (Platform and Version): macOS 10.14.2

* Output of `node_modules/.bin/electron --version` on last known working Electron version (if applicable): 2.0.7

### Expected behavior

I should be able to call `app.setAccessibilitySupportEnabled(true)` during initialization, and the application should start and stay open.

### Actual behavior

The application starts and exits immediately if `app.setAccessibilitySupportEnabled(true)` is called during initialization. Same for passing in `false`.

### How to reproduce

Here is a simple project that shows this error. The application behaves as expected (does not exit immediately) when this line is commented out:
https://github.com/marisademeglio/electron4-setA11yTreeEnabled/blob/master/src/main/main.js#L27

  $ git clone https://github.com/marisademeglio/electron4-setA11yTreeEnabled.git
  $ yarn install
  $ yarn start

atom/browser/api/atom_api_app.cc
v8::Local<v8::Value> val,
                     Browser::LoginItemSettings* out) {
    mate::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));
    return true;
  }
  static v8::Local<v8::Value> ToV8(v8::Isolate* isolate,
                                   Browser::LoginItemSettings val) {
    mate::Dictionary dict = mate::Dictionary::CreateEmpty(isolate);
    dict.Set("openAtLogin", val.open_at_login);
    dict.Set("openAsHidden", val.open_as_hidden);
    dict.Set("restoreState", val.restore_state);
    dict.Set("wasOpenedAtLogin", val.opened_at_login);
    dict.Set("wasOpenedAsHidden", val.opened_as_hidden);
    return dict.GetHandle();
  }
};
template <>
struct Converter<content::CertificateRequestResultType> {
  static bool FromV8(v8::Isolate* isolate,