fix(goTo): validate target correctly when vue is minified (#3638)
fix(goTo): validate target correctly when vue is minified (#3638)

constructor.name isn't reliable for type checking when function names
are minified, but vue components will always have an _isVue property

Also fixed position calculation of elements in relative contexts,
Element.offsetTop only returns the offset to the offsetParent in such
cases

Fixes #3611
Webifi/vuetify,Webifi/vuetify,Phlow2001/vuetify,Phlow2001/vuetify,Phlow2001/vuetify,vuetifyjs/vuetify,vuetifyjs/vuetify,vuetifyjs/vuetify,vuetifyjs/vuetify,Phlow2001/vuetify,Webifi/vuetify