### 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 for an issue that matches the one I want to file, without success.

### Issue Details

It would appear that `app.focus()` stopped working in Electron 6, and remains broken in Electron 8.

* **Electron Version:**
  * 8.0.3
* **Operating System:**
  * macOS
* **Last Known Working Electron version:**
  * 5.0.13

### Expected Behavior
`app.focus()` should bring the application to the foreground.

### Actual Behavior
`app.focus()` does nothing.

### To Reproduce

Fiddle: https://gist.github.com/a772265b312329e3f3bc1feb7b6aff7d

1) Start this fiddle.
2) As soon as the window pops up, select another application so that Electron is in the background.
3) Within 5 seconds, the app will attempt to focus itself to no avail.

shell/browser/browser_win.cc
#include "shell/browser/browser.h"
#include <windows.h>  
#include <atlbase.h>
#include <shlobj.h>
#include <shobjidl.h>
#include "base/base_paths.h"
#include "base/file_version_info.h"
#include "base/files/file_path.h"
#include "base/path_service.h"
#include "base/strings/string_util.h"
#include "base/strings/stringprintf.h"
#include "base/strings/utf_string_conversions.h"
#include "base/threading/thread_restrictions.h"
#include "base/win/registry.h"
#include "base/win/win_util.h"
#include "base/win/windows_version.h"
#include "electron/electron_version.h"
#include "shell/browser/ui/message_box.h"
#include "shell/browser/ui/win/jump_list.h"
#include "shell/common/application_info.h"
#include "shell/common/gin_helper/arguments.h"
#include "shell/common/skia_util.h"
#include "ui/events/keycodes/keyboard_code_conversion_win.h"
namespace electron {
namespace {
BOOL CALLBACK WindowsEnumerationHandler(HWND hwnd, LPARAM param) {