Created by: 719media
Sometimes, a dropdown menu is used without an associated button/toggle.
For example, I am using bootstrap menu with class .dropdown-menu (.SELECTOR_MENU), but am showing the dropdown manually (there is no toggle button). When I arrow down within this menu, I am hitting an error Cannot read property '_selectMenuItem' of null.
With this change, the absence of a toggle doesn't throw this error (and therefore prevent other key handlers from firing).