loader不支持webp格式

[xiongsongsong]

Version

3.0.0-beta.9

Reproduction link

https://user-images.githubusercontent.com/342509/40229979-842af4cc-5ac8-11e8-8e7b-67e2ef98e9d4.png

Steps to reproduce

section {
   background-image: url(./img/default-bg.webp);
}

What is expected?

error  in ./src/components/Login/img/default-bg.webp

Module parse failed: Unexpected character '' (1:4)
You may need an appropriate loader to handle this file type.

What is actually happening?

Normal