Url params in child route undefined

[dimensi]

Version

2.8.0 & 3.0.0

Reproduction link

http://jsfiddle.net/xfmcLgjd/4/

Steps to reproduce

1. Create route with optional param
2. Create in route, child route with optional param

What is expected?

id === 10  
mode === 'test'  
modeId === 1  

What is actually happening?

id === 10
mode === undefined
modeId === undefined

---

With problem only from 2.8.0 and only with child.

[posva]

For some reason, declaring the props mode and modeId on the parent route view fixes the issue
edit: I cleared out the conversation because it was my bad, sorry 😆

[yyx990803]

Duplicate of #1800