[Bug Report] table height unlimited growth with "height='auto' & show-summary"

### Element UI version
2.14.1

### OS/Browsers version
Mac/chrome

### Vue version
2.5.17

### Reproduction Link
https://codepen.io/codepen-io-wPhilipp/pen/jOMymMg

### Steps to reproduce
1.click the button "切换数据"
2.table will unlimited growth when data is "[]"

### What is Expected?
table's height is 60px when no data

### What is actually happening?
table's height is grow unlimited

#20567