[2.6-beta] regression: component without slots re-renders when parent updates

[KaelWD]

Version

2.6.0-beta.3

Reproduction link

https://codepen.io/anon/pen/JxEpJK?editors=1011

Steps to reproduce

• click the "root" button

What is expected?

"update root" should be logged

What is actually happening?

"update ChildComponent" is also logged

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If you add v-slot:default it works as expected: https://codepen.io/anon/pen/exgVVm?editors=1011
Vue 2.5.22 also works correctly: https://codepen.io/anon/pen/KJaQQL?editors=1011