* Electron version: 1.4.14
* Operating system: Windows 8.1

### Expected behavior

A fullscreen transparent window should be transparent.

### Actual behavior

The window is not transparent (has a white background).

### How to reproduce

```
electron.app.on("ready", function () {
    var win = new BrowserWindow({
        show: true,
        frame: false,
        fullscreen: true,
        transparent: true
    });
});
```

Refs https://github.com/electron/electron/issues/8321#issuecomment-273615701


atom/browser/native_window_views.cc
#if defined(OS_WIN)
  base::win::ScopedComPtr<ITaskbarList> taskbar;
  if (FAILED(taskbar.CreateInstance(CLSID_TaskbarList, NULL,
                                    CLSCTX_INPROC_SERVER)) ||
      FAILED(taskbar->HrInit()))
    return;
  if (skip) {
    taskbar->DeleteTab(GetAcceleratedWidget());
  } else {
    taskbar->AddTab(GetAcceleratedWidget());
    taskbar_host_.RestoreThumbarButtons(GetAcceleratedWidget());
  }
#elif defined(USE_X11)
  SetWMSpecState(GetAcceleratedWidget(), skip,
                 GetAtom("_NET_WM_STATE_SKIP_TASKBAR"));
#endif
}
void NativeWindowViews::SetKiosk(bool kiosk) {