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### Issue Details

* **Electron Version:**
  * 12.0.0-beta.1 to 12.0.0-beta.6
* **Operating System:**
  * Windows 10 (2004) 
* **Last Known Working Electron version:**
  * 11.x.x (all of them)

### Expected Behavior
Click on Menu Item opens the submenu of this item

### Actual Behavior
Clicking on menu set with Menu.setApplicationMenu(Menu.buildFromTemplate(topLevelItems)); is not possible. Pressing "ALT" Highlights the menu but nothing more happens

### To Reproduce
Build Application with menu
shell/browser/ui/views/menu_bar.cc
views::AccessiblePaneView::RemovePaneFocus();
  SetAcceleratorVisibility(false);
  std::set<ui::KeyboardCode> unreg;
  for (auto* child : GetChildrenInZOrder()) {
    auto* button = static_cast<SubmenuButton*>(child);
    bool shifted = false;
    auto keycode =
        electron::KeyboardCodeFromCharCode(button->accelerator(), &shifted);
    if (keycode != ui::VKEY_UNKNOWN && unreg.find(keycode) != unreg.end()) {
      unreg.insert(keycode);
      focus_manager()->UnregisterAccelerator(
          ui::Accelerator(keycode, ui::EF_NONE), this);
    }
  }
  focus_manager()->UnregisterAccelerator(
      ui::Accelerator(ui::VKEY_MENU, ui::EF_ALT_DOWN), this);
}
const char* MenuBar::GetClassName() const {