navigator.mimeTypes.hasOwnProperty('__ember_meta__')

navigator.mimeTypes.__ember_meta__

navigator.mimeTypes.hasOwnProperty('__foobar__')

navigator.mimeTypes.__foobar__

navigator.mimeTypes.hasOwnProperty('__this_is_a_joke_firefox_you_cant_be_serious__')

navigator.mimeTypes.__this_is_a_joke_firefox_you_cant_be_serious__