Element: [Bug, Report], Wrong, display, about, NumberInput, with, slot (prepend, and, append)

[kankk]

Element UI version

1.3.5

OS/Browsers version

Chrome 58.0.3029.110 (64-bit)

Vue version

2.3.4

Reproduction Link

https://jsfiddle.net/pj71jkyw/

Steps to reproduce

<el-input-number>
  <template slot="prepend">Number:</template>
  <template slot="append">个</template>
</el-input-number>

What is Expected?

Display like with slot (prepend or append)

What is actually happening?

It is not displayed properly. the slot with append will overflow the increase button and decrease button. Btw, it is not normal way to use slot in NumberInput, but I think it will be work after I read the resource. Please feel free to let me know is it the normal way to use slot in NumberInput.