[Bug Report] Expansion panel animation with 1 item

[TiagoXavi]

Versions and Environment

Vuetify: 1.4.1
Vue: 2.5.21
Browsers: Chrome 71.0.3578.98
OS: Windows 10

Steps to reproduce

Click on "open" and "close" repeatedly.

Expected Behavior

Smooth contract

Actual Behavior

Some times the close animation don't happen.

Reproduction Link

https://codepen.io/tiagoxavi/pen/EGdjbZ

[johnleider]

This is indicative of how expand-transition behaves when working with elements that use v-show. @KaelWD I looked into this and the only reproduce-able step was having only 1 element. 2 or more and the transition works fine.

[KaelWD]

2 elements worked because the other one would call a reflow at the same time. Firefox handles them a bit differently hence #6049