[Bug Report] Inconsistent behavior when using server-side rendering

[egoist]

Element UI version

1.2.5

OS/Browsers version

macOS latest / chrome

Vue version

2.2.5

Reproduction Link

https://github.com/ream/ream/tree/dev/examples/with-element-ui

Steps to reproduce

You can clone that repo and cd into the example or download with following command:

curl https://codeload.github.com/ream/ream/tar.gz/dev | tar -xz --strip=2 ream-dev/examples/with-element-ui
cd with-element-ui
yarn
yarn dev

What is Expected?

works like a charm

What is actually happening?

Check out GIF:

It can be reproduced in Nuxt.js as well