refactor(v-toolbar): refactored shouldScroll property
refactor(v-toolbar): refactored shouldScroll property

added better flow for determining state, added comments

vuetifyjs/vuetify,vuetifyjs/vuetify,Phlow2001/vuetify,KaelWD/vuetify,Webifi/vuetify,Webifi/vuetify,Phlow2001/vuetify,Webifi/vuetify,Phlow2001/vuetify,Phlow2001/vuetify,KaelWD/vuetify,KaelWD/vuetify,vuetifyjs/vuetify,vuetifyjs/vuetify