[Bug] v-snackbar elevation

[Manoah Tervoort]

<v-snackbar elevation="24"/> is transformed to <v-snackbar content-class="elevation-24">
<v-snackbar :elevation="24"/> is transformed to <v-snackbar :content-class="24 && 'elevation-24'">

Both should be transformed to <v-snackbar class="elevation-24"> (class instead of content-class)

And if class already exists it should be added to class (class="some-class elevation-24")