### Issue Details
in frameless windows 
While setting browserview style to draggable by webkit-app-region : drag. the area won't be draggable after that
and it can not move main window 
### Electron Version:
11.0.1
### Operating System:
Windows 10 (1803)
Last Known Working Electron version:
not found
### Expected Behavior
Browser view moves the main window while I set the style of the body or one of the area to
-webkit-app-region: drag;

### Actual Behavior
nothing happen in browserview after styling -webkit-app-region: drag;

I know it is mention that in 11 version it is fixed. but it still dosn't work 

### To Reproduce
https://gist.github.com/pejmanpesyan/8540aad65e7c6980c45f23e5eaafafb9

shell/browser/native_window_views.cc
const std::string& level,
                                       int relativeLevel) {
  bool level_changed = z_order != widget()->GetZOrderLevel();
  widget()->SetZOrderLevel(z_order);
#if defined(OS_WIN)
  
  behind_task_bar_ = false;
  if (z_order != ui::ZOrderLevel::kNormal) {
    
    
    static const std::vector<std::string> levels = {
        "floating", "torn-off-menu", "modal-panel", "main-menu", "status"};
    behind_task_bar_ = base::Contains(levels, level);
  }
#endif
  MoveBehindTaskBarIfNeeded();
  
  
  if (level_changed)
    NativeWindow::NotifyWindowAlwaysOnTopChanged();
}
ui::ZOrderLevel NativeWindowViews::GetZOrderLevel() {
  return widget()->GetZOrderLevel();
}
void NativeWindowViews::Center() {