* 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,
                     JumpListCategory* out) {
    mate::Dictionary dict;
    if (!ConvertFromV8(isolate, val, &dict))
      return false;
    if (dict.Get("name", &(out->name)) && out->name.empty())
      return false;
    if (!dict.Get("type", &(out->type))) {
      if (out->name.empty())
        out->type = JumpListCategory::Type::TASKS;
      else
        out->type = JumpListCategory::Type::CUSTOM;
    }
    if ((out->type == JumpListCategory::Type::TASKS) ||
        (out->type == JumpListCategory::Type::CUSTOM)) {
      if (!dict.Get("items", &(out->items)))
        return false;
    }
    return true;
  }
};
template <>
struct Converter<JumpListResult> {
  static v8::Local<v8::Value> ToV8(v8::Isolate* isolate, JumpListResult val) {