[Bug Report] VDataTable expand slot doesn't work with normal element

[lzhoucs]

expand slot can't be used on normal elements.

Versions and Environment

Vuetify: https://unpkg.com/vuetify@1.1.14/dist/vuetify.min.js
Vue: https://unpkg.com/vue@2.5.17/dist/vue.js
Browsers: Version 68.0.3440.106 (Official Build) (64-bit)
OS: macos 10.13

Steps to reproduce

• Go to https://codepen.io/lzhoucs/pen/mGeBqz
• Click rows on the first table to expand, it works
• Click rows on the 2nd table to expand, it doesn't work

Expected Behavior

The 2nd table rows expand should work, as vue supports slots on normal elements: https://vuejs.org/v2/guide/components-slots.html

Actual Behavior

The 2nd table rows are not expandable

Reproduction Link

Go to https://codepen.io/lzhoucs/pen/mGeBqz

Additional Comments:

On the other hand, items slots work with normal elements in real projects, but not on codepen. For example, with the link above, the table brearks as soon as items slot is changed to the following to remove template:

        <tr slot="items" slot-scope="props" @click="props.expanded = !props.expanded">
          <td>{{ props.item.name }}</td>
          <td>{{ props.item.calories }}</td>
        </tr>

but it works in real projects with the same vue/vuetify version. Not sure if it is related to the expand slot issue.

[KaelWD]

This is why typescript is good, that needs to be an array. First is template, second is bare span:

Edit: turns out TS wouldn't have caught this, thanks Vue: vuejs/vue#8644