Remove button focus border on firefox (#1844)
Remove button focus border on firefox (#1844)

Fixes #1843
vuetifyjs/vuetify,Phlow2001/vuetify,Webifi/vuetify,KaelWD/vuetify,KaelWD/vuetify,Phlow2001/vuetify,Webifi/vuetify,Webifi/vuetify,vuetifyjs/vuetify,vuetifyjs/vuetify,Phlow2001/vuetify,Phlow2001/vuetify,azaars/vuetify,azaars/vuetify,vuetifyjs/vuetify,KaelWD/vuetify