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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/submenu_button.cc
base::char16* accelerator,
                                         int* start,
                                         int* end) const {
  int pos, span;
  base::string16 trimmed =
      gfx::LocateAndRemoveAcceleratorChar(text, &pos, &span);
  if (pos > -1 && span != 0) {
    *accelerator = base::ToUpperASCII(trimmed[pos]);
    GetCharacterPosition(trimmed, pos, start);
    GetCharacterPosition(trimmed, pos + span, end);
    return true;
  }
  return false;
}
void SubmenuButton::GetCharacterPosition(const base::string16& text,
                                         int index,
                                         int* pos) const {
  int height = 0;
  gfx::Canvas::SizeStringInt(text.substr(0, index), gfx::FontList(), pos,
                             &height, 0, 0);
}
}